Update copyright dates (again)

[thirdparty/xfsprogs-dev.git] / libxfs / xfs_ialloc_btree.c

/*
 * Copyright (c) 2000-2001 Silicon Graphics, Inc.  All Rights Reserved.
 * 
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 * 
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * 
 * Further, this software is distributed without any warranty that it is
 * free of the rightful claim of any third person regarding infringement
 * or the like.  Any license provided herein, whether implied or
 * otherwise, applies only to this software file.  Patent licenses, if
 * any, provided herein do not apply to combinations of this program with
 * other software, or any other product whatsoever.
 * 
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write the Free Software Foundation, Inc., 59
 * Temple Place - Suite 330, Boston MA 02111-1307, USA.
 * 
 * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
 * Mountain View, CA  94043, or:
 * 
 * http://www.sgi.com 
 * 
 * For further information regarding this notice, see: 
 * 
 * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
 */

/*
 * Inode allocation management for XFS.
 */
#include <xfs.h>

/*
 * Insert one record/level.  Return information to the caller
 * allowing the next level up to proceed if necessary.
 */
STATIC int                              /* error */
xfs_inobt_insrec(
        xfs_btree_cur_t         *cur,   /* btree cursor */
        int                     level,  /* level to insert record at */
        xfs_agblock_t           *bnop,  /* i/o: block number inserted */
        xfs_inobt_rec_t         *recp,  /* i/o: record data inserted */
        xfs_btree_cur_t         **curp, /* output: new cursor replacing cur */
        int                     *stat)  /* success/failure */
{
        xfs_inobt_block_t       *block; /* btree block record/key lives in */
        xfs_buf_t               *bp;    /* buffer for block */
        int                     error;  /* error return value */
        int                     i;      /* loop index */
        xfs_inobt_key_t         key;    /* key value being inserted */
        xfs_inobt_key_t         *kp=NULL;       /* pointer to btree keys */
        xfs_agblock_t           nbno;   /* block number of allocated block */
        xfs_btree_cur_t         *ncur;  /* new cursor to be used at next lvl */
        xfs_inobt_key_t         nkey;   /* new key value, from split */
        xfs_inobt_rec_t         nrec;   /* new record value, for caller */
        int                     optr;   /* old ptr value */
        xfs_inobt_ptr_t         *pp;    /* pointer to btree addresses */
        int                     ptr;    /* index in btree block for this rec */
        xfs_inobt_rec_t         *rp=NULL;       /* pointer to btree records */

        /*
         * If we made it to the root level, allocate a new root block
         * and we're done.
         */
        if (level >= cur->bc_nlevels) {
                error = xfs_inobt_newroot(cur, &i);
                *bnop = NULLAGBLOCK;
                *stat = i;
                return error;
        }
        /*
         * Make a key out of the record data to be inserted, and save it.
         */
        key.ir_startino = recp->ir_startino; /* INT_: direct copy */
        optr = ptr = cur->bc_ptrs[level];
        /*
         * If we're off the left edge, return failure.
         */
        if (ptr == 0) {
                *stat = 0;
                return 0;
        }
        /*
         * Get pointers to the btree buffer and block.
         */
        bp = cur->bc_bufs[level];
        block = XFS_BUF_TO_INOBT_BLOCK(bp);
#ifdef DEBUG
        if ((error = xfs_btree_check_sblock(cur, block, level, bp)))
                return error;
        /* 
         * Check that the new entry is being inserted in the right place.
         */
        if (ptr <= INT_GET(block->bb_numrecs, ARCH_CONVERT)) {
                if (level == 0) {
                        rp = XFS_INOBT_REC_ADDR(block, ptr, cur);
                        xfs_btree_check_rec(cur->bc_btnum, recp, rp);
                } else {
                        kp = XFS_INOBT_KEY_ADDR(block, ptr, cur);
                        xfs_btree_check_key(cur->bc_btnum, &key, kp);
                }
        }
#endif
        nbno = NULLAGBLOCK;
        ncur = (xfs_btree_cur_t *)0;
        /*
         * If the block is full, we can't insert the new entry until we
         * make the block un-full.
         */
        if (INT_GET(block->bb_numrecs, ARCH_CONVERT) == XFS_INOBT_BLOCK_MAXRECS(level, cur)) {
                /*
                 * First, try shifting an entry to the right neighbor.
                 */
                if ((error = xfs_inobt_rshift(cur, level, &i)))
                        return error;
                if (i) {
                        /* nothing */
                }
                /*
                 * Next, try shifting an entry to the left neighbor.
                 */
                else {
                        if ((error = xfs_inobt_lshift(cur, level, &i)))
                                return error;
                        if (i) {
                                optr = ptr = cur->bc_ptrs[level];
                        } else {
                                /*
                                 * Next, try splitting the current block
                                 * in half. If this works we have to
                                 * re-set our variables because
                                 * we could be in a different block now.
                                 */
                                if ((error = xfs_inobt_split(cur, level, &nbno,
                                                &nkey, &ncur, &i)))
                                        return error;
                                if (i) {
                                        bp = cur->bc_bufs[level];
                                        block = XFS_BUF_TO_INOBT_BLOCK(bp);
#ifdef DEBUG
                                        if ((error = xfs_btree_check_sblock(cur,
                                                        block, level, bp)))
                                                return error;
#endif
                                        ptr = cur->bc_ptrs[level];
                                        nrec.ir_startino = nkey.ir_startino; /* INT_: direct copy */
                                } else {
                                        /*
                                         * Otherwise the insert fails.
                                         */
                                        *stat = 0;
                                        return 0;
                                }
                        }
                }
        }
        /*
         * At this point we know there's room for our new entry in the block
         * we're pointing at.
         */
        if (level > 0) {
                /*
                 * It's a non-leaf entry.  Make a hole for the new data
                 * in the key and ptr regions of the block.
                 */
                kp = XFS_INOBT_KEY_ADDR(block, 1, cur);
                pp = XFS_INOBT_PTR_ADDR(block, 1, cur);
#ifdef DEBUG
                for (i = INT_GET(block->bb_numrecs, ARCH_CONVERT); i >= ptr; i--) {
                        if ((error = xfs_btree_check_sptr(cur, INT_GET(pp[i - 1], ARCH_CONVERT), level)))
                                return error;
                }
#endif
                ovbcopy(&kp[ptr - 1], &kp[ptr],
                        (INT_GET(block->bb_numrecs, ARCH_CONVERT) - ptr + 1) * sizeof(*kp));
                ovbcopy(&pp[ptr - 1], &pp[ptr],
                        (INT_GET(block->bb_numrecs, ARCH_CONVERT) - ptr + 1) * sizeof(*pp));
                /*
                 * Now stuff the new data in, bump numrecs and log the new data.
                 */
#ifdef DEBUG
                if ((error = xfs_btree_check_sptr(cur, *bnop, level)))
                        return error;
#endif
                kp[ptr - 1] = key; /* INT_: struct copy */
                INT_SET(pp[ptr - 1], ARCH_CONVERT, *bnop);
                INT_MOD(block->bb_numrecs, ARCH_CONVERT, +1);
                xfs_inobt_log_keys(cur, bp, ptr, INT_GET(block->bb_numrecs, ARCH_CONVERT));
                xfs_inobt_log_ptrs(cur, bp, ptr, INT_GET(block->bb_numrecs, ARCH_CONVERT));
        } else {
                /*
                 * It's a leaf entry.  Make a hole for the new record.
                 */
                rp = XFS_INOBT_REC_ADDR(block, 1, cur);
                ovbcopy(&rp[ptr - 1], &rp[ptr],
                        (INT_GET(block->bb_numrecs, ARCH_CONVERT) - ptr + 1) * sizeof(*rp));
                /*
                 * Now stuff the new record in, bump numrecs
                 * and log the new data.
                 */
                rp[ptr - 1] = *recp; /* INT_: struct copy */
                INT_MOD(block->bb_numrecs, ARCH_CONVERT, +1);
                xfs_inobt_log_recs(cur, bp, ptr, INT_GET(block->bb_numrecs, ARCH_CONVERT));
        }
        /*
         * Log the new number of records in the btree header.
         */
        xfs_inobt_log_block(cur->bc_tp, bp, XFS_BB_NUMRECS);
#ifdef DEBUG
        /*
         * Check that the key/record is in the right place, now.
         */
        if (ptr < INT_GET(block->bb_numrecs, ARCH_CONVERT)) {
                if (level == 0)
                        xfs_btree_check_rec(cur->bc_btnum, rp + ptr - 1,
                                rp + ptr);
                else
                        xfs_btree_check_key(cur->bc_btnum, kp + ptr - 1,
                                kp + ptr);
        }
#endif
        /*
         * If we inserted at the start of a block, update the parents' keys.
         */
        if (optr == 1 && (error = xfs_inobt_updkey(cur, &key, level + 1)))
                return error;
        /*
         * Return the new block number, if any.
         * If there is one, give back a record value and a cursor too.
         */
        *bnop = nbno;
        if (nbno != NULLAGBLOCK) {
                *recp = nrec; /* INT_: struct copy */
                *curp = ncur;
        }
        *stat = 1;
        return 0;
}

/*
 * Log header fields from a btree block.
 */
STATIC void
xfs_inobt_log_block(
        xfs_trans_t             *tp,    /* transaction pointer */
        xfs_buf_t               *bp,    /* buffer containing btree block */
        int                     fields) /* mask of fields: XFS_BB_... */
{
        int                     first;  /* first byte offset logged */
        int                     last;   /* last byte offset logged */
        static const short      offsets[] = {   /* table of offsets */
                offsetof(xfs_inobt_block_t, bb_magic),
                offsetof(xfs_inobt_block_t, bb_level),
                offsetof(xfs_inobt_block_t, bb_numrecs),
                offsetof(xfs_inobt_block_t, bb_leftsib),
                offsetof(xfs_inobt_block_t, bb_rightsib),
                sizeof(xfs_inobt_block_t)
        };

        xfs_btree_offsets(fields, offsets, XFS_BB_NUM_BITS, &first, &last);
        xfs_trans_log_buf(tp, bp, first, last);
}

/*
 * Log keys from a btree block (nonleaf).
 */
STATIC void
xfs_inobt_log_keys(
        xfs_btree_cur_t         *cur,   /* btree cursor */
        xfs_buf_t               *bp,    /* buffer containing btree block */
        int                     kfirst, /* index of first key to log */
        int                     klast)  /* index of last key to log */
{
        xfs_inobt_block_t       *block; /* btree block to log from */
        int                     first;  /* first byte offset logged */
        xfs_inobt_key_t         *kp;    /* key pointer in btree block */
        int                     last;   /* last byte offset logged */

        block = XFS_BUF_TO_INOBT_BLOCK(bp);
        kp = XFS_INOBT_KEY_ADDR(block, 1, cur);
        first = (int)((xfs_caddr_t)&kp[kfirst - 1] - (xfs_caddr_t)block);
        last = (int)(((xfs_caddr_t)&kp[klast] - 1) - (xfs_caddr_t)block);
        xfs_trans_log_buf(cur->bc_tp, bp, first, last);
}

/*
 * Log block pointer fields from a btree block (nonleaf).
 */
STATIC void
xfs_inobt_log_ptrs(
        xfs_btree_cur_t         *cur,   /* btree cursor */
        xfs_buf_t               *bp,    /* buffer containing btree block */
        int                     pfirst, /* index of first pointer to log */
        int                     plast)  /* index of last pointer to log */
{
        xfs_inobt_block_t       *block; /* btree block to log from */
        int                     first;  /* first byte offset logged */
        int                     last;   /* last byte offset logged */
        xfs_inobt_ptr_t         *pp;    /* block-pointer pointer in btree blk */

        block = XFS_BUF_TO_INOBT_BLOCK(bp);
        pp = XFS_INOBT_PTR_ADDR(block, 1, cur);
        first = (int)((xfs_caddr_t)&pp[pfirst - 1] - (xfs_caddr_t)block);
        last = (int)(((xfs_caddr_t)&pp[plast] - 1) - (xfs_caddr_t)block);
        xfs_trans_log_buf(cur->bc_tp, bp, first, last);
}

/*
 * Log records from a btree block (leaf).
 */
STATIC void
xfs_inobt_log_recs(
        xfs_btree_cur_t         *cur,   /* btree cursor */
        xfs_buf_t               *bp,    /* buffer containing btree block */
        int                     rfirst, /* index of first record to log */
        int                     rlast)  /* index of last record to log */
{
        xfs_inobt_block_t       *block; /* btree block to log from */
        int                     first;  /* first byte offset logged */
        int                     last;   /* last byte offset logged */
        xfs_inobt_rec_t         *rp;    /* record pointer for btree block */

        block = XFS_BUF_TO_INOBT_BLOCK(bp);
        rp = XFS_INOBT_REC_ADDR(block, 1, cur);
        first = (int)((xfs_caddr_t)&rp[rfirst - 1] - (xfs_caddr_t)block);
        last = (int)(((xfs_caddr_t)&rp[rlast] - 1) - (xfs_caddr_t)block);
        xfs_trans_log_buf(cur->bc_tp, bp, first, last);
}

/*
 * Lookup the record.  The cursor is made to point to it, based on dir.
 * Return 0 if can't find any such record, 1 for success.
 */
STATIC int                              /* error */
xfs_inobt_lookup(
        xfs_btree_cur_t         *cur,   /* btree cursor */
        xfs_lookup_t            dir,    /* <=, ==, or >= */
        int                     *stat)  /* success/failure */
{
        xfs_agblock_t           agbno;  /* a.g. relative btree block number */
        xfs_agnumber_t          agno;   /* allocation group number */
        xfs_inobt_block_t       *block=NULL;    /* current btree block */
        int                     diff;   /* difference for the current key */
        int                     error;  /* error return value */
        int                     keyno=0;        /* current key number */
        int                     level;  /* level in the btree */
        xfs_mount_t             *mp;    /* file system mount point */

        /*
         * Get the allocation group header, and the root block number.
         */
        mp = cur->bc_mp;
        {
                xfs_agi_t       *agi;   /* a.g. inode header */

                agi = XFS_BUF_TO_AGI(cur->bc_private.i.agbp);
                agno = INT_GET(agi->agi_seqno, ARCH_CONVERT);
                agbno = INT_GET(agi->agi_root, ARCH_CONVERT);
        }
        /*
         * Iterate over each level in the btree, starting at the root.
         * For each level above the leaves, find the key we need, based
         * on the lookup record, then follow the corresponding block
         * pointer down to the next level.
         */
        for (level = cur->bc_nlevels - 1, diff = 1; level >= 0; level--) {
                xfs_buf_t       *bp;    /* buffer pointer for btree block */
                xfs_daddr_t             d;      /* disk address of btree block */

                /*
                 * Get the disk address we're looking for.
                 */
                d = XFS_AGB_TO_DADDR(mp, agno, agbno);
                /*
                 * If the old buffer at this level is for a different block,
                 * throw it away, otherwise just use it.
                 */
                bp = cur->bc_bufs[level];
                if (bp && XFS_BUF_ADDR(bp) != d)
                        bp = (xfs_buf_t *)0;
                if (!bp) {
                        /*
                         * Need to get a new buffer.  Read it, then 
                         * set it in the cursor, releasing the old one.
                         */
                        if ((error = xfs_btree_read_bufs(mp, cur->bc_tp,
                                        agno, agbno, 0, &bp, XFS_INO_BTREE_REF)))
                                return error;
                        xfs_btree_setbuf(cur, level, bp);
                        /*
                         * Point to the btree block, now that we have the buffer
                         */
                        block = XFS_BUF_TO_INOBT_BLOCK(bp);
                        if ((error = xfs_btree_check_sblock(cur, block, level,
                                        bp)))
                                return error;
                } else
                        block = XFS_BUF_TO_INOBT_BLOCK(bp);
                /*
                 * If we already had a key match at a higher level, we know
                 * we need to use the first entry in this block.
                 */
                if (diff == 0)
                        keyno = 1;
                /*
                 * Otherwise we need to search this block.  Do a binary search.
                 */
                else {
                        int             high;   /* high entry number */
                        xfs_inobt_key_t *kkbase=NULL;/* base of keys in block */
                        xfs_inobt_rec_t *krbase=NULL;/* base of records in block */
                        int             low;    /* low entry number */

                        /*
                         * Get a pointer to keys or records.
                         */
                        if (level > 0)
                                kkbase = XFS_INOBT_KEY_ADDR(block, 1, cur);
                        else
                                krbase = XFS_INOBT_REC_ADDR(block, 1, cur);
                        /*
                         * Set low and high entry numbers, 1-based.
                         */
                        low = 1;
                        if (!(high = INT_GET(block->bb_numrecs, ARCH_CONVERT))) {
                                /*
                                 * If the block is empty, the tree must
                                 * be an empty leaf.
                                 */
                                ASSERT(level == 0 && cur->bc_nlevels == 1);
                                cur->bc_ptrs[0] = dir != XFS_LOOKUP_LE;
                                *stat = 0;
                                return 0;
                        }
                        /*
                         * Binary search the block.
                         */
                        while (low <= high) {
                                xfs_agino_t     startino;       /* key value */

                                /*
                                 * keyno is average of low and high.
                                 */
                                keyno = (low + high) >> 1;
                                /*
                                 * Get startino.
                                 */
                                if (level > 0) {
                                        xfs_inobt_key_t *kkp;

                                        kkp = kkbase + keyno - 1;
                                        startino = INT_GET(kkp->ir_startino, ARCH_CONVERT);
                                } else {
                                        xfs_inobt_rec_t *krp;

                                        krp = krbase + keyno - 1;
                                        startino = INT_GET(krp->ir_startino, ARCH_CONVERT);
                                }
                                /*
                                 * Compute difference to get next direction.
                                 */
                                diff = (int)startino - cur->bc_rec.i.ir_startino;
                                /*
                                 * Less than, move right.
                                 */
                                if (diff < 0)
                                        low = keyno + 1;
                                /*
                                 * Greater than, move left.
                                 */
                                else if (diff > 0)
                                        high = keyno - 1;
                                /*
                                 * Equal, we're done.
                                 */
                                else
                                        break;
                        }
                }
                /*
                 * If there are more levels, set up for the next level
                 * by getting the block number and filling in the cursor.
                 */
                if (level > 0) {
                        /*
                         * If we moved left, need the previous key number,
                         * unless there isn't one.
                         */
                        if (diff > 0 && --keyno < 1)
                                keyno = 1;
                        agbno = INT_GET(*XFS_INOBT_PTR_ADDR(block, keyno, cur), ARCH_CONVERT);
#ifdef DEBUG
                        if ((error = xfs_btree_check_sptr(cur, agbno, level)))
                                return error;
#endif
                        cur->bc_ptrs[level] = keyno;
                }
        }
        /*
         * Done with the search.
         * See if we need to adjust the results.
         */
        if (dir != XFS_LOOKUP_LE && diff < 0) {
                keyno++;
                /*
                 * If ge search and we went off the end of the block, but it's
                 * not the last block, we're in the wrong block.
                 */
                if (dir == XFS_LOOKUP_GE &&
                    keyno > INT_GET(block->bb_numrecs, ARCH_CONVERT) &&
                    INT_GET(block->bb_rightsib, ARCH_CONVERT) != NULLAGBLOCK) {
                        int     i;

                        cur->bc_ptrs[0] = keyno;
                        if ((error = xfs_inobt_increment(cur, 0, &i)))
                                return error;
                        ASSERT(i == 1);
                        *stat = 1;
                        return 0;
                }
        }
        else if (dir == XFS_LOOKUP_LE && diff > 0)
                keyno--;
        cur->bc_ptrs[0] = keyno;
        /*
         * Return if we succeeded or not.
         */
        if (keyno == 0 || keyno > INT_GET(block->bb_numrecs, ARCH_CONVERT))
                *stat = 0;
        else
                *stat = ((dir != XFS_LOOKUP_EQ) || (diff == 0));
        return 0;
}

/*
 * Move 1 record left from cur/level if possible.
 * Update cur to reflect the new path.
 */
STATIC int                              /* error */
xfs_inobt_lshift(
        xfs_btree_cur_t         *cur,   /* btree cursor */
        int                     level,  /* level to shift record on */
        int                     *stat)  /* success/failure */
{
        int                     error;  /* error return value */
#ifdef DEBUG
        int                     i;      /* loop index */
#endif
        xfs_inobt_key_t         key;    /* key value for leaf level upward */
        xfs_buf_t               *lbp;   /* buffer for left neighbor block */
        xfs_inobt_block_t       *left;  /* left neighbor btree block */
        xfs_inobt_key_t         *lkp=NULL;      /* key pointer for left block */
        xfs_inobt_ptr_t         *lpp;   /* address pointer for left block */
        xfs_inobt_rec_t         *lrp=NULL;      /* record pointer for left block */
        int                     nrec;   /* new number of left block entries */
        xfs_buf_t               *rbp;   /* buffer for right (current) block */
        xfs_inobt_block_t       *right; /* right (current) btree block */
        xfs_inobt_key_t         *rkp=NULL;      /* key pointer for right block */
        xfs_inobt_ptr_t         *rpp=NULL;      /* address pointer for right block */
        xfs_inobt_rec_t         *rrp=NULL;      /* record pointer for right block */

        /*
         * Set up variables for this block as "right".
         */
        rbp = cur->bc_bufs[level];
        right = XFS_BUF_TO_INOBT_BLOCK(rbp);
#ifdef DEBUG
        if ((error = xfs_btree_check_sblock(cur, right, level, rbp)))
                return error;
#endif
        /*
         * If we've got no left sibling then we can't shift an entry left.
         */
        if (INT_GET(right->bb_leftsib, ARCH_CONVERT) == NULLAGBLOCK) {
                *stat = 0;
                return 0;
        }
        /*
         * If the cursor entry is the one that would be moved, don't 
         * do it... it's too complicated.
         */
        if (cur->bc_ptrs[level] <= 1) {
                *stat = 0;
                return 0;
        }
        /*
         * Set up the left neighbor as "left".
         */
        if ((error = xfs_btree_read_bufs(cur->bc_mp, cur->bc_tp,
                        cur->bc_private.i.agno, INT_GET(right->bb_leftsib, ARCH_CONVERT), 0, &lbp,
                        XFS_INO_BTREE_REF)))
                return error;
        left = XFS_BUF_TO_INOBT_BLOCK(lbp);
        if ((error = xfs_btree_check_sblock(cur, left, level, lbp)))
                return error;
        /*
         * If it's full, it can't take another entry.
         */
        if (INT_GET(left->bb_numrecs, ARCH_CONVERT) == XFS_INOBT_BLOCK_MAXRECS(level, cur)) {
                *stat = 0;
                return 0;
        }
        nrec = INT_GET(left->bb_numrecs, ARCH_CONVERT) + 1;
        /*
         * If non-leaf, copy a key and a ptr to the left block.
         */
        if (level > 0) {
                lkp = XFS_INOBT_KEY_ADDR(left, nrec, cur);
                rkp = XFS_INOBT_KEY_ADDR(right, 1, cur);
                *lkp = *rkp;
                xfs_inobt_log_keys(cur, lbp, nrec, nrec);
                lpp = XFS_INOBT_PTR_ADDR(left, nrec, cur);
                rpp = XFS_INOBT_PTR_ADDR(right, 1, cur);
#ifdef DEBUG
                if ((error = xfs_btree_check_sptr(cur, INT_GET(*rpp, ARCH_CONVERT), level)))
                        return error;
#endif
                *lpp = *rpp; /* INT_: no-change copy */
                xfs_inobt_log_ptrs(cur, lbp, nrec, nrec);
        }
        /*
         * If leaf, copy a record to the left block.
         */
        else {
                lrp = XFS_INOBT_REC_ADDR(left, nrec, cur);
                rrp = XFS_INOBT_REC_ADDR(right, 1, cur);
                *lrp = *rrp;
                xfs_inobt_log_recs(cur, lbp, nrec, nrec);
        }
        /*
         * Bump and log left's numrecs, decrement and log right's numrecs.
         */
        INT_MOD(left->bb_numrecs, ARCH_CONVERT, +1);
        xfs_inobt_log_block(cur->bc_tp, lbp, XFS_BB_NUMRECS);
#ifdef DEBUG
        if (level > 0)
                xfs_btree_check_key(cur->bc_btnum, lkp - 1, lkp);
        else
                xfs_btree_check_rec(cur->bc_btnum, lrp - 1, lrp);
#endif
        INT_MOD(right->bb_numrecs, ARCH_CONVERT, -1);
        xfs_inobt_log_block(cur->bc_tp, rbp, XFS_BB_NUMRECS);
        /*
         * Slide the contents of right down one entry.
         */
        if (level > 0) {
#ifdef DEBUG
                for (i = 0; i < INT_GET(right->bb_numrecs, ARCH_CONVERT); i++) {
                        if ((error = xfs_btree_check_sptr(cur, INT_GET(rpp[i + 1], ARCH_CONVERT),
                                        level)))
                                return error;
                }
#endif
                ovbcopy(rkp + 1, rkp, INT_GET(right->bb_numrecs, ARCH_CONVERT) * sizeof(*rkp));
                ovbcopy(rpp + 1, rpp, INT_GET(right->bb_numrecs, ARCH_CONVERT) * sizeof(*rpp));
                xfs_inobt_log_keys(cur, rbp, 1, INT_GET(right->bb_numrecs, ARCH_CONVERT));
                xfs_inobt_log_ptrs(cur, rbp, 1, INT_GET(right->bb_numrecs, ARCH_CONVERT));
        } else {
                ovbcopy(rrp + 1, rrp, INT_GET(right->bb_numrecs, ARCH_CONVERT) * sizeof(*rrp));
                xfs_inobt_log_recs(cur, rbp, 1, INT_GET(right->bb_numrecs, ARCH_CONVERT));
                key.ir_startino = rrp->ir_startino; /* INT_: direct copy */
                rkp = &key;
        }
        /*
         * Update the parent key values of right.
         */
        if ((error = xfs_inobt_updkey(cur, rkp, level + 1)))
                return error;
        /*
         * Slide the cursor value left one.
         */
        cur->bc_ptrs[level]--;
        *stat = 1;
        return 0;
}

/*
 * Allocate a new root block, fill it in.
 */
STATIC int                              /* error */
xfs_inobt_newroot(
        xfs_btree_cur_t         *cur,   /* btree cursor */
        int                     *stat)  /* success/failure */
{
        xfs_agi_t               *agi;   /* a.g. inode header */
        xfs_alloc_arg_t         args;   /* allocation argument structure */
        xfs_inobt_block_t       *block; /* one half of the old root block */
        xfs_buf_t               *bp;    /* buffer containing block */
        int                     error;  /* error return value */
        xfs_inobt_key_t         *kp;    /* btree key pointer */
        xfs_agblock_t           lbno;   /* left block number */
        xfs_buf_t               *lbp;   /* left buffer pointer */
        xfs_inobt_block_t       *left;  /* left btree block */
        xfs_buf_t               *nbp;   /* new (root) buffer */
        xfs_inobt_block_t       *new;   /* new (root) btree block */
        int                     nptr;   /* new value for key index, 1 or 2 */
        xfs_inobt_ptr_t         *pp;    /* btree address pointer */
        xfs_agblock_t           rbno;   /* right block number */
        xfs_buf_t               *rbp;   /* right buffer pointer */
        xfs_inobt_block_t       *right; /* right btree block */
        xfs_inobt_rec_t         *rp;    /* btree record pointer */

        ASSERT(cur->bc_nlevels < XFS_IN_MAXLEVELS(cur->bc_mp));

        /*
         * Get a block & a buffer.
         */
        agi = XFS_BUF_TO_AGI(cur->bc_private.i.agbp);
        args.tp = cur->bc_tp;
        args.mp = cur->bc_mp;
        args.fsbno = XFS_AGB_TO_FSB(args.mp, cur->bc_private.i.agno,
                INT_GET(agi->agi_root, ARCH_CONVERT));
        args.mod = args.minleft = args.alignment = args.total = args.wasdel =
                args.isfl = args.userdata = args.minalignslop = 0;
        args.minlen = args.maxlen = args.prod = 1;
        args.type = XFS_ALLOCTYPE_NEAR_BNO;
        if ((error = xfs_alloc_vextent(&args)))
                return error;
        /*
         * None available, we fail.
         */
        if (args.fsbno == NULLFSBLOCK) {
                *stat = 0;
                return 0;
        }
        ASSERT(args.len == 1);
        nbp = xfs_btree_get_bufs(args.mp, args.tp, args.agno, args.agbno, 0);
        new = XFS_BUF_TO_INOBT_BLOCK(nbp);
        /*
         * Set the root data in the a.g. inode structure.
         */
        INT_SET(agi->agi_root, ARCH_CONVERT, args.agbno);
        INT_MOD(agi->agi_level, ARCH_CONVERT, 1);
        xfs_ialloc_log_agi(args.tp, cur->bc_private.i.agbp,
                XFS_AGI_ROOT | XFS_AGI_LEVEL);
        /*
         * At the previous root level there are now two blocks: the old
         * root, and the new block generated when it was split.
         * We don't know which one the cursor is pointing at, so we
         * set up variables "left" and "right" for each case.
         */
        bp = cur->bc_bufs[cur->bc_nlevels - 1];
        block = XFS_BUF_TO_INOBT_BLOCK(bp);
#ifdef DEBUG
        if ((error = xfs_btree_check_sblock(cur, block, cur->bc_nlevels - 1, bp)))
                return error;
#endif
        if (INT_GET(block->bb_rightsib, ARCH_CONVERT) != NULLAGBLOCK) {
                /*
                 * Our block is left, pick up the right block.
                 */
                lbp = bp;
                lbno = XFS_DADDR_TO_AGBNO(args.mp, XFS_BUF_ADDR(lbp));
                left = block;
                rbno = INT_GET(left->bb_rightsib, ARCH_CONVERT);
                if ((error = xfs_btree_read_bufs(args.mp, args.tp, args.agno,
                                rbno, 0, &rbp, XFS_INO_BTREE_REF)))
                        return error;
                bp = rbp;
                right = XFS_BUF_TO_INOBT_BLOCK(rbp);
                if ((error = xfs_btree_check_sblock(cur, right,
                                cur->bc_nlevels - 1, rbp)))
                        return error;
                nptr = 1;
        } else {
                /*
                 * Our block is right, pick up the left block.
                 */
                rbp = bp;
                rbno = XFS_DADDR_TO_AGBNO(args.mp, XFS_BUF_ADDR(rbp));
                right = block;
                lbno = INT_GET(right->bb_leftsib, ARCH_CONVERT);
                if ((error = xfs_btree_read_bufs(args.mp, args.tp, args.agno,
                                lbno, 0, &lbp, XFS_INO_BTREE_REF)))
                        return error;
                bp = lbp;
                left = XFS_BUF_TO_INOBT_BLOCK(lbp);
                if ((error = xfs_btree_check_sblock(cur, left,
                                cur->bc_nlevels - 1, lbp)))
                        return error;
                nptr = 2;
        }
        /*
         * Fill in the new block's btree header and log it.
         */
        INT_SET(new->bb_magic, ARCH_CONVERT, xfs_magics[cur->bc_btnum]);
        INT_SET(new->bb_level, ARCH_CONVERT, (__uint16_t)cur->bc_nlevels);
        INT_SET(new->bb_numrecs, ARCH_CONVERT, 2);
        INT_SET(new->bb_leftsib, ARCH_CONVERT, NULLAGBLOCK);
        INT_SET(new->bb_rightsib, ARCH_CONVERT, NULLAGBLOCK);
        xfs_inobt_log_block(args.tp, nbp, XFS_BB_ALL_BITS);
        ASSERT(lbno != NULLAGBLOCK && rbno != NULLAGBLOCK);
        /*
         * Fill in the key data in the new root.
         */
        kp = XFS_INOBT_KEY_ADDR(new, 1, cur);
        if (INT_GET(left->bb_level, ARCH_CONVERT) > 0) {
                kp[0] = *XFS_INOBT_KEY_ADDR(left, 1, cur); /* INT_: struct copy */
                kp[1] = *XFS_INOBT_KEY_ADDR(right, 1, cur); /* INT_: struct copy */
        } else {
                rp = XFS_INOBT_REC_ADDR(left, 1, cur);
                INT_COPY(kp[0].ir_startino, rp->ir_startino, ARCH_CONVERT);
                rp = XFS_INOBT_REC_ADDR(right, 1, cur);
                INT_COPY(kp[1].ir_startino, rp->ir_startino, ARCH_CONVERT);
        }
        xfs_inobt_log_keys(cur, nbp, 1, 2);
        /*
         * Fill in the pointer data in the new root.
         */
        pp = XFS_INOBT_PTR_ADDR(new, 1, cur);
        INT_SET(pp[0], ARCH_CONVERT, lbno);
        INT_SET(pp[1], ARCH_CONVERT, rbno);
        xfs_inobt_log_ptrs(cur, nbp, 1, 2);
        /*
         * Fix up the cursor.
         */
        xfs_btree_setbuf(cur, cur->bc_nlevels, nbp);
        cur->bc_ptrs[cur->bc_nlevels] = nptr;
        cur->bc_nlevels++;
        *stat = 1;
        return 0;
}

/*
 * Move 1 record right from cur/level if possible.
 * Update cur to reflect the new path.
 */
STATIC int                              /* error */
xfs_inobt_rshift(
        xfs_btree_cur_t         *cur,   /* btree cursor */
        int                     level,  /* level to shift record on */
        int                     *stat)  /* success/failure */
{
        int                     error;  /* error return value */
        int                     i;      /* loop index */
        xfs_inobt_key_t         key;    /* key value for leaf level upward */
        xfs_buf_t               *lbp;   /* buffer for left (current) block */
        xfs_inobt_block_t       *left;  /* left (current) btree block */
        xfs_inobt_key_t         *lkp;   /* key pointer for left block */
        xfs_inobt_ptr_t         *lpp;   /* address pointer for left block */
        xfs_inobt_rec_t         *lrp;   /* record pointer for left block */
        xfs_buf_t               *rbp;   /* buffer for right neighbor block */
        xfs_inobt_block_t       *right; /* right neighbor btree block */
        xfs_inobt_key_t         *rkp;   /* key pointer for right block */
        xfs_inobt_ptr_t         *rpp;   /* address pointer for right block */
        xfs_inobt_rec_t         *rrp=NULL;      /* record pointer for right block */
        xfs_btree_cur_t         *tcur;  /* temporary cursor */

        /*
         * Set up variables for this block as "left".
         */
        lbp = cur->bc_bufs[level];
        left = XFS_BUF_TO_INOBT_BLOCK(lbp);
#ifdef DEBUG
        if ((error = xfs_btree_check_sblock(cur, left, level, lbp)))
                return error;
#endif
        /*
         * If we've got no right sibling then we can't shift an entry right.
         */
        if (INT_GET(left->bb_rightsib, ARCH_CONVERT) == NULLAGBLOCK) {
                *stat = 0;
                return 0;
        }
        /*
         * If the cursor entry is the one that would be moved, don't
         * do it... it's too complicated.
         */
        if (cur->bc_ptrs[level] >= INT_GET(left->bb_numrecs, ARCH_CONVERT)) {
                *stat = 0;
                return 0;
        }
        /*
         * Set up the right neighbor as "right".
         */
        if ((error = xfs_btree_read_bufs(cur->bc_mp, cur->bc_tp,
                        cur->bc_private.i.agno, INT_GET(left->bb_rightsib, ARCH_CONVERT), 0, &rbp,
                        XFS_INO_BTREE_REF)))
                return error;
        right = XFS_BUF_TO_INOBT_BLOCK(rbp);
        if ((error = xfs_btree_check_sblock(cur, right, level, rbp)))
                return error;
        /*
         * If it's full, it can't take another entry.
         */
        if (INT_GET(right->bb_numrecs, ARCH_CONVERT) == XFS_INOBT_BLOCK_MAXRECS(level, cur)) {
                *stat = 0;
                return 0;
        }
        /*
         * Make a hole at the start of the right neighbor block, then
         * copy the last left block entry to the hole.
         */
        if (level > 0) {
                lkp = XFS_INOBT_KEY_ADDR(left, INT_GET(left->bb_numrecs, ARCH_CONVERT), cur);
                lpp = XFS_INOBT_PTR_ADDR(left, INT_GET(left->bb_numrecs, ARCH_CONVERT), cur);
                rkp = XFS_INOBT_KEY_ADDR(right, 1, cur);
                rpp = XFS_INOBT_PTR_ADDR(right, 1, cur);
#ifdef DEBUG
                for (i = INT_GET(right->bb_numrecs, ARCH_CONVERT) - 1; i >= 0; i--) {
                        if ((error = xfs_btree_check_sptr(cur, INT_GET(rpp[i], ARCH_CONVERT), level)))
                                return error;
                }
#endif
                ovbcopy(rkp, rkp + 1, INT_GET(right->bb_numrecs, ARCH_CONVERT) * sizeof(*rkp));
                ovbcopy(rpp, rpp + 1, INT_GET(right->bb_numrecs, ARCH_CONVERT) * sizeof(*rpp));
#ifdef DEBUG
                if ((error = xfs_btree_check_sptr(cur, INT_GET(*lpp, ARCH_CONVERT), level)))
                        return error;
#endif
                *rkp = *lkp; /* INT_: no change copy */
                *rpp = *lpp; /* INT_: no change copy */
                xfs_inobt_log_keys(cur, rbp, 1, INT_GET(right->bb_numrecs, ARCH_CONVERT) + 1);
                xfs_inobt_log_ptrs(cur, rbp, 1, INT_GET(right->bb_numrecs, ARCH_CONVERT) + 1);
        } else {
                lrp = XFS_INOBT_REC_ADDR(left, INT_GET(left->bb_numrecs, ARCH_CONVERT), cur);
                rrp = XFS_INOBT_REC_ADDR(right, 1, cur);
                ovbcopy(rrp, rrp + 1, INT_GET(right->bb_numrecs, ARCH_CONVERT) * sizeof(*rrp));
                *rrp = *lrp;
                xfs_inobt_log_recs(cur, rbp, 1, INT_GET(right->bb_numrecs, ARCH_CONVERT) + 1);
                key.ir_startino = rrp->ir_startino; /* INT_: direct copy */
                rkp = &key;
        }
        /*
         * Decrement and log left's numrecs, bump and log right's numrecs.
         */
        INT_MOD(left->bb_numrecs, ARCH_CONVERT, -1);
        xfs_inobt_log_block(cur->bc_tp, lbp, XFS_BB_NUMRECS);
        INT_MOD(right->bb_numrecs, ARCH_CONVERT, +1);
#ifdef DEBUG
        if (level > 0)
                xfs_btree_check_key(cur->bc_btnum, rkp, rkp + 1);
        else
                xfs_btree_check_rec(cur->bc_btnum, rrp, rrp + 1);
#endif
        xfs_inobt_log_block(cur->bc_tp, rbp, XFS_BB_NUMRECS);
        /*
         * Using a temporary cursor, update the parent key values of the
         * block on the right.
         */
        if ((error = xfs_btree_dup_cursor(cur, &tcur)))
                return error;
        xfs_btree_lastrec(tcur, level);
        if ((error = xfs_inobt_increment(tcur, level, &i)) ||
            (error = xfs_inobt_updkey(tcur, rkp, level + 1))) {
                xfs_btree_del_cursor(tcur, XFS_BTREE_ERROR);
                return error;
        }
        xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
        *stat = 1;
        return 0;
}

/*
 * Split cur/level block in half.
 * Return new block number and its first record (to be inserted into parent).
 */
STATIC int                              /* error */
xfs_inobt_split(
        xfs_btree_cur_t         *cur,   /* btree cursor */
        int                     level,  /* level to split */
        xfs_agblock_t           *bnop,  /* output: block number allocated */
        xfs_inobt_key_t         *keyp,  /* output: first key of new block */
        xfs_btree_cur_t         **curp, /* output: new cursor */
        int                     *stat)  /* success/failure */
{
        xfs_alloc_arg_t         args;   /* allocation argument structure */
        int                     error;  /* error return value */
        int                     i;      /* loop index/record number */
        xfs_agblock_t           lbno;   /* left (current) block number */
        xfs_buf_t               *lbp;   /* buffer for left block */
        xfs_inobt_block_t       *left;  /* left (current) btree block */
        xfs_inobt_key_t         *lkp;   /* left btree key pointer */
        xfs_inobt_ptr_t         *lpp;   /* left btree address pointer */
        xfs_inobt_rec_t         *lrp;   /* left btree record pointer */
        xfs_buf_t               *rbp;   /* buffer for right block */
        xfs_inobt_block_t       *right; /* right (new) btree block */
        xfs_inobt_key_t         *rkp;   /* right btree key pointer */
        xfs_inobt_ptr_t         *rpp;   /* right btree address pointer */
        xfs_inobt_rec_t         *rrp;   /* right btree record pointer */

        /*
         * Set up left block (current one).
         */
        lbp = cur->bc_bufs[level];
        args.tp = cur->bc_tp;
        args.mp = cur->bc_mp;
        lbno = XFS_DADDR_TO_AGBNO(args.mp, XFS_BUF_ADDR(lbp));
        /*
         * Allocate the new block.
         * If we can't do it, we're toast.  Give up.
         */
        args.fsbno = XFS_AGB_TO_FSB(args.mp, cur->bc_private.i.agno, lbno);
        args.mod = args.minleft = args.alignment = args.total = args.wasdel =
                args.isfl = args.userdata = args.minalignslop = 0;
        args.minlen = args.maxlen = args.prod = 1;
        args.type = XFS_ALLOCTYPE_NEAR_BNO;
        if ((error = xfs_alloc_vextent(&args)))
                return error;
        if (args.fsbno == NULLFSBLOCK) {
                *stat = 0;
                return 0;
        }
        ASSERT(args.len == 1);
        rbp = xfs_btree_get_bufs(args.mp, args.tp, args.agno, args.agbno, 0);
        /*
         * Set up the new block as "right".
         */
        right = XFS_BUF_TO_INOBT_BLOCK(rbp);
        /*
         * "Left" is the current (according to the cursor) block.
         */
        left = XFS_BUF_TO_INOBT_BLOCK(lbp);
#ifdef DEBUG
        if ((error = xfs_btree_check_sblock(cur, left, level, lbp)))
                return error;
#endif
        /*
         * Fill in the btree header for the new block.
         */
        INT_SET(right->bb_magic, ARCH_CONVERT, xfs_magics[cur->bc_btnum]);
        right->bb_level = left->bb_level; /* INT_: direct copy */
        INT_SET(right->bb_numrecs, ARCH_CONVERT, (__uint16_t)(INT_GET(left->bb_numrecs, ARCH_CONVERT) / 2));
        /*
         * Make sure that if there's an odd number of entries now, that
         * each new block will have the same number of entries.
         */
        if ((INT_GET(left->bb_numrecs, ARCH_CONVERT) & 1) &&
            cur->bc_ptrs[level] <= INT_GET(right->bb_numrecs, ARCH_CONVERT) + 1)
                INT_MOD(right->bb_numrecs, ARCH_CONVERT, +1);
        i = INT_GET(left->bb_numrecs, ARCH_CONVERT) - INT_GET(right->bb_numrecs, ARCH_CONVERT) + 1;
        /*
         * For non-leaf blocks, copy keys and addresses over to the new block.
         */
        if (level > 0) {
                lkp = XFS_INOBT_KEY_ADDR(left, i, cur);
                lpp = XFS_INOBT_PTR_ADDR(left, i, cur);
                rkp = XFS_INOBT_KEY_ADDR(right, 1, cur);
                rpp = XFS_INOBT_PTR_ADDR(right, 1, cur);
#ifdef DEBUG
                for (i = 0; i < INT_GET(right->bb_numrecs, ARCH_CONVERT); i++) {
                        if ((error = xfs_btree_check_sptr(cur, INT_GET(lpp[i], ARCH_CONVERT), level)))
                                return error;
                }
#endif
                bcopy(lkp, rkp, INT_GET(right->bb_numrecs, ARCH_CONVERT) * sizeof(*rkp));
                bcopy(lpp, rpp, INT_GET(right->bb_numrecs, ARCH_CONVERT) * sizeof(*rpp));
                xfs_inobt_log_keys(cur, rbp, 1, INT_GET(right->bb_numrecs, ARCH_CONVERT));
                xfs_inobt_log_ptrs(cur, rbp, 1, INT_GET(right->bb_numrecs, ARCH_CONVERT));
                *keyp = *rkp;
        }
        /*
         * For leaf blocks, copy records over to the new block.
         */
        else {
                lrp = XFS_INOBT_REC_ADDR(left, i, cur);
                rrp = XFS_INOBT_REC_ADDR(right, 1, cur);
                bcopy(lrp, rrp, INT_GET(right->bb_numrecs, ARCH_CONVERT) * sizeof(*rrp));
                xfs_inobt_log_recs(cur, rbp, 1, INT_GET(right->bb_numrecs, ARCH_CONVERT));
                keyp->ir_startino = rrp->ir_startino; /* INT_: direct copy */
        }
        /*
         * Find the left block number by looking in the buffer.
         * Adjust numrecs, sibling pointers.
         */
        INT_MOD(left->bb_numrecs, ARCH_CONVERT, -(INT_GET(right->bb_numrecs, ARCH_CONVERT)));
        right->bb_rightsib = left->bb_rightsib; /* INT_: direct copy */
        INT_SET(left->bb_rightsib, ARCH_CONVERT, args.agbno);
        INT_SET(right->bb_leftsib, ARCH_CONVERT, lbno);
        xfs_inobt_log_block(args.tp, rbp, XFS_BB_ALL_BITS);
        xfs_inobt_log_block(args.tp, lbp, XFS_BB_NUMRECS | XFS_BB_RIGHTSIB);
        /*
         * If there's a block to the new block's right, make that block
         * point back to right instead of to left.
         */
        if (INT_GET(right->bb_rightsib, ARCH_CONVERT) != NULLAGBLOCK) {
                xfs_inobt_block_t       *rrblock;       /* rr btree block */
                xfs_buf_t               *rrbp;          /* buffer for rrblock */

                if ((error = xfs_btree_read_bufs(args.mp, args.tp, args.agno,
                                INT_GET(right->bb_rightsib, ARCH_CONVERT), 0, &rrbp,
                                XFS_INO_BTREE_REF)))
                        return error;
                rrblock = XFS_BUF_TO_INOBT_BLOCK(rrbp);
                if ((error = xfs_btree_check_sblock(cur, rrblock, level, rrbp)))
                        return error;
                INT_SET(rrblock->bb_leftsib, ARCH_CONVERT, args.agbno);
                xfs_inobt_log_block(args.tp, rrbp, XFS_BB_LEFTSIB);
        }
        /*
         * If the cursor is really in the right block, move it there.
         * If it's just pointing past the last entry in left, then we'll
         * insert there, so don't change anything in that case.
         */
        if (cur->bc_ptrs[level] > INT_GET(left->bb_numrecs, ARCH_CONVERT) + 1) {
                xfs_btree_setbuf(cur, level, rbp);
                cur->bc_ptrs[level] -= INT_GET(left->bb_numrecs, ARCH_CONVERT);
        }
        /*
         * If there are more levels, we'll need another cursor which refers
         * the right block, no matter where this cursor was.
         */
        if (level + 1 < cur->bc_nlevels) {
                if ((error = xfs_btree_dup_cursor(cur, curp)))
                        return error;
                (*curp)->bc_ptrs[level + 1]++;
        }
        *bnop = args.agbno;
        *stat = 1;
        return 0;
}

/*
 * Update keys at all levels from here to the root along the cursor's path.
 */
STATIC int                              /* error */
xfs_inobt_updkey(
        xfs_btree_cur_t         *cur,   /* btree cursor */
        xfs_inobt_key_t         *keyp,  /* new key value to update to */
        int                     level)  /* starting level for update */
{
        int                     ptr;    /* index of key in block */

        /*
         * Go up the tree from this level toward the root.
         * At each level, update the key value to the value input.
         * Stop when we reach a level where the cursor isn't pointing
         * at the first entry in the block.
         */
        for (ptr = 1; ptr == 1 && level < cur->bc_nlevels; level++) {
                xfs_buf_t               *bp;    /* buffer for block */
                xfs_inobt_block_t       *block; /* btree block */
#ifdef DEBUG
                int                     error;  /* error return value */
#endif
                xfs_inobt_key_t         *kp;    /* ptr to btree block keys */

                bp = cur->bc_bufs[level];
                block = XFS_BUF_TO_INOBT_BLOCK(bp);
#ifdef DEBUG
                if ((error = xfs_btree_check_sblock(cur, block, level, bp)))
                        return error;
#endif
                ptr = cur->bc_ptrs[level];
                kp = XFS_INOBT_KEY_ADDR(block, ptr, cur);
                *kp = *keyp;
                xfs_inobt_log_keys(cur, bp, ptr, ptr);
        }
        return 0;
}

/*
 * Externally visible routines.
 */

/*
 * Decrement cursor by one record at the level.
 * For nonzero levels the leaf-ward information is untouched.
 */
int                                     /* error */
xfs_inobt_decrement(
        xfs_btree_cur_t         *cur,   /* btree cursor */
        int                     level,  /* level in btree, 0 is leaf */
        int                     *stat)  /* success/failure */
{
        xfs_inobt_block_t       *block; /* btree block */
        int                     error;
        int                     lev;    /* btree level */

        ASSERT(level < cur->bc_nlevels);
        /*
         * Read-ahead to the left at this level.
         */
        xfs_btree_readahead(cur, level, XFS_BTCUR_LEFTRA);
        /*
         * Decrement the ptr at this level.  If we're still in the block
         * then we're done.
         */
        if (--cur->bc_ptrs[level] > 0) {
                *stat = 1;
                return 0;
        }
        /*
         * Get a pointer to the btree block.
         */
        block = XFS_BUF_TO_INOBT_BLOCK(cur->bc_bufs[level]);
#ifdef DEBUG
        if ((error = xfs_btree_check_sblock(cur, block, level,
                        cur->bc_bufs[level])))
                return error;
#endif
        /*
         * If we just went off the left edge of the tree, return failure.
         */
        if (INT_GET(block->bb_leftsib, ARCH_CONVERT) == NULLAGBLOCK) {
                *stat = 0;
                return 0;
        }
        /*
         * March up the tree decrementing pointers.
         * Stop when we don't go off the left edge of a block.
         */
        for (lev = level + 1; lev < cur->bc_nlevels; lev++) {
                if (--cur->bc_ptrs[lev] > 0)
                        break;
                /*
                 * Read-ahead the left block, we're going to read it
                 * in the next loop.
                 */
                xfs_btree_readahead(cur, lev, XFS_BTCUR_LEFTRA);
        }
        /*
         * If we went off the root then we are seriously confused.
         */
        ASSERT(lev < cur->bc_nlevels);
        /*
         * Now walk back down the tree, fixing up the cursor's buffer
         * pointers and key numbers.
         */
        for (block = XFS_BUF_TO_INOBT_BLOCK(cur->bc_bufs[lev]); lev > level; ) {
                xfs_agblock_t   agbno;  /* block number of btree block */
                xfs_buf_t       *bp;    /* buffer containing btree block */

                agbno = INT_GET(*XFS_INOBT_PTR_ADDR(block, cur->bc_ptrs[lev], cur), ARCH_CONVERT);
                if ((error = xfs_btree_read_bufs(cur->bc_mp, cur->bc_tp,
                                cur->bc_private.i.agno, agbno, 0, &bp,
                                XFS_INO_BTREE_REF)))
                        return error;
                lev--;
                xfs_btree_setbuf(cur, lev, bp);
                block = XFS_BUF_TO_INOBT_BLOCK(bp);
                if ((error = xfs_btree_check_sblock(cur, block, lev, bp)))
                        return error;
                cur->bc_ptrs[lev] = INT_GET(block->bb_numrecs, ARCH_CONVERT);
        }
        *stat = 1;
        return 0;
}

/* 
 * Get the data from the pointed-to record.
 */
int                                     /* error */
xfs_inobt_get_rec(
        xfs_btree_cur_t         *cur,   /* btree cursor */
        xfs_agino_t             *ino,   /* output: starting inode of chunk */
        __int32_t               *fcnt,  /* output: number of free inodes */
        xfs_inofree_t           *free,  /* output: free inode mask */
        int                     *stat,  /* output: success/failure */
        xfs_arch_t              arch)   /* input: architecture */
{
        xfs_inobt_block_t       *block; /* btree block */
        xfs_buf_t               *bp;    /* buffer containing btree block */
#ifdef DEBUG
        int                     error;  /* error return value */
#endif
        int                     ptr;    /* record number */
        xfs_inobt_rec_t         *rec;   /* record data */

        bp = cur->bc_bufs[0];
        ptr = cur->bc_ptrs[0];
        block = XFS_BUF_TO_INOBT_BLOCK(bp);
#ifdef DEBUG
        if ((error = xfs_btree_check_sblock(cur, block, 0, bp)))
                return error;
#endif
        /*
         * Off the right end or left end, return failure.
         */
        if (ptr > INT_GET(block->bb_numrecs, ARCH_CONVERT) || ptr <= 0) {
                *stat = 0;
                return 0;
        }
        /*
         * Point to the record and extract its data.
         */
        rec = XFS_INOBT_REC_ADDR(block, ptr, cur);
        ASSERT(arch == ARCH_NOCONVERT || arch == ARCH_CONVERT);
        if (arch == ARCH_NOCONVERT) {
            *ino = INT_GET(rec->ir_startino, ARCH_CONVERT);
            *fcnt = INT_GET(rec->ir_freecount, ARCH_CONVERT);
            *free = INT_GET(rec->ir_free, ARCH_CONVERT);
        } else {
            INT_COPY(*ino, rec->ir_startino, ARCH_CONVERT);
            INT_COPY(*fcnt, rec->ir_freecount, ARCH_CONVERT);
            INT_COPY(*free, rec->ir_free, ARCH_CONVERT);
        }
        *stat = 1;
        return 0;
}

/*
 * Increment cursor by one record at the level.
 * For nonzero levels the leaf-ward information is untouched.
 */
int                                     /* error */
xfs_inobt_increment(
        xfs_btree_cur_t         *cur,   /* btree cursor */
        int                     level,  /* level in btree, 0 is leaf */
        int                     *stat)  /* success/failure */
{
        xfs_inobt_block_t       *block; /* btree block */
        xfs_buf_t               *bp;    /* buffer containing btree block */
        int                     error;  /* error return value */
        int                     lev;    /* btree level */

        ASSERT(level < cur->bc_nlevels);
        /*
         * Read-ahead to the right at this level.
         */
        xfs_btree_readahead(cur, level, XFS_BTCUR_RIGHTRA);
        /*
         * Get a pointer to the btree block.
         */
        bp = cur->bc_bufs[level];
        block = XFS_BUF_TO_INOBT_BLOCK(bp);
#ifdef DEBUG
        if ((error = xfs_btree_check_sblock(cur, block, level, bp)))
                return error;
#endif
        /*
         * Increment the ptr at this level.  If we're still in the block
         * then we're done.
         */
        if (++cur->bc_ptrs[level] <= INT_GET(block->bb_numrecs, ARCH_CONVERT)) {
                *stat = 1;
                return 0;
        }
        /*
         * If we just went off the right edge of the tree, return failure.
         */
        if (INT_GET(block->bb_rightsib, ARCH_CONVERT) == NULLAGBLOCK) {
                *stat = 0;
                return 0;
        }
        /*
         * March up the tree incrementing pointers.
         * Stop when we don't go off the right edge of a block.
         */
        for (lev = level + 1; lev < cur->bc_nlevels; lev++) {
                bp = cur->bc_bufs[lev];
                block = XFS_BUF_TO_INOBT_BLOCK(bp);
#ifdef DEBUG
                if ((error = xfs_btree_check_sblock(cur, block, lev, bp)))
                        return error;
#endif
                if (++cur->bc_ptrs[lev] <= INT_GET(block->bb_numrecs, ARCH_CONVERT))
                        break;
                /*
                 * Read-ahead the right block, we're going to read it
                 * in the next loop.
                 */
                xfs_btree_readahead(cur, lev, XFS_BTCUR_RIGHTRA);
        }
        /*
         * If we went off the root then we are seriously confused.
         */
        ASSERT(lev < cur->bc_nlevels);
        /*
         * Now walk back down the tree, fixing up the cursor's buffer
         * pointers and key numbers.
         */
        for (bp = cur->bc_bufs[lev], block = XFS_BUF_TO_INOBT_BLOCK(bp);
             lev > level; ) {
                xfs_agblock_t   agbno;  /* block number of btree block */

                agbno = INT_GET(*XFS_INOBT_PTR_ADDR(block, cur->bc_ptrs[lev], cur), ARCH_CONVERT);
                if ((error = xfs_btree_read_bufs(cur->bc_mp, cur->bc_tp,
                                cur->bc_private.i.agno, agbno, 0, &bp,
                                XFS_INO_BTREE_REF)))
                        return error;
                lev--;
                xfs_btree_setbuf(cur, lev, bp);
                block = XFS_BUF_TO_INOBT_BLOCK(bp);
                if ((error = xfs_btree_check_sblock(cur, block, lev, bp)))
                        return error;
                cur->bc_ptrs[lev] = 1;
        }
        *stat = 1;
        return 0;
}

/*
 * Insert the current record at the point referenced by cur.
 * The cursor may be inconsistent on return if splits have been done.
 */
int                                     /* error */
xfs_inobt_insert(
        xfs_btree_cur_t *cur,           /* btree cursor */
        int             *stat)          /* success/failure */
{
        int             error;          /* error return value */
        int             i;              /* result value, 0 for failure */
        int             level;          /* current level number in btree */
        xfs_agblock_t   nbno;           /* new block number (split result) */
        xfs_btree_cur_t *ncur;          /* new cursor (split result) */
        xfs_inobt_rec_t nrec;           /* record being inserted this level */
        xfs_btree_cur_t *pcur;          /* previous level's cursor */

        level = 0;
        nbno = NULLAGBLOCK;
        INT_SET(nrec.ir_startino, ARCH_CONVERT, cur->bc_rec.i.ir_startino);
        INT_SET(nrec.ir_freecount, ARCH_CONVERT, cur->bc_rec.i.ir_freecount);
        INT_SET(nrec.ir_free, ARCH_CONVERT, cur->bc_rec.i.ir_free);
        ncur = (xfs_btree_cur_t *)0;
        pcur = cur;
        /*
         * Loop going up the tree, starting at the leaf level.
         * Stop when we don't get a split block, that must mean that
         * the insert is finished with this level.
         */
        do {
                /*
                 * Insert nrec/nbno into this level of the tree.
                 * Note if we fail, nbno will be null.
                 */
                if ((error = xfs_inobt_insrec(pcur, level++, &nbno, &nrec, &ncur,
                                &i))) {
                        if (pcur != cur)
                                xfs_btree_del_cursor(pcur, XFS_BTREE_ERROR);
                        return error;
                }
                /*
                 * See if the cursor we just used is trash.
                 * Can't trash the caller's cursor, but otherwise we should
                 * if ncur is a new cursor or we're about to be done.
                 */
                if (pcur != cur && (ncur || nbno == NULLAGBLOCK)) {
                        cur->bc_nlevels = pcur->bc_nlevels;
                        xfs_btree_del_cursor(pcur, XFS_BTREE_NOERROR);
                }
                /*
                 * If we got a new cursor, switch to it.
                 */
                if (ncur) {
                        pcur = ncur;
                        ncur = (xfs_btree_cur_t *)0;
                }
        } while (nbno != NULLAGBLOCK);
        *stat = i;
        return 0;
}

/*
 * Lookup the record equal to ino in the btree given by cur.
 */
int                                     /* error */
xfs_inobt_lookup_eq(
        xfs_btree_cur_t *cur,           /* btree cursor */
        xfs_agino_t     ino,            /* starting inode of chunk */
        __int32_t       fcnt,           /* free inode count */
        xfs_inofree_t   free,           /* free inode mask */
        int             *stat)          /* success/failure */
{
        cur->bc_rec.i.ir_startino = ino;
        cur->bc_rec.i.ir_freecount = fcnt;
        cur->bc_rec.i.ir_free = free;
        return xfs_inobt_lookup(cur, XFS_LOOKUP_EQ, stat);
}

/*
 * Lookup the first record greater than or equal to ino
 * in the btree given by cur.
 */
int                                     /* error */
xfs_inobt_lookup_ge(
        xfs_btree_cur_t *cur,           /* btree cursor */
        xfs_agino_t     ino,            /* starting inode of chunk */
        __int32_t       fcnt,           /* free inode count */
        xfs_inofree_t   free,           /* free inode mask */
        int             *stat)          /* success/failure */
{
        cur->bc_rec.i.ir_startino = ino;
        cur->bc_rec.i.ir_freecount = fcnt;
        cur->bc_rec.i.ir_free = free;
        return xfs_inobt_lookup(cur, XFS_LOOKUP_GE, stat);
}

/*
 * Lookup the first record less than or equal to ino
 * in the btree given by cur.
 */
int                                     /* error */
xfs_inobt_lookup_le(
        xfs_btree_cur_t *cur,           /* btree cursor */
        xfs_agino_t     ino,            /* starting inode of chunk */
        __int32_t       fcnt,           /* free inode count */
        xfs_inofree_t   free,           /* free inode mask */
        int             *stat)          /* success/failure */
{
        cur->bc_rec.i.ir_startino = ino;
        cur->bc_rec.i.ir_freecount = fcnt;
        cur->bc_rec.i.ir_free = free;
        return xfs_inobt_lookup(cur, XFS_LOOKUP_LE, stat);
}

/*
 * Update the record referred to by cur, to the value given
 * by [ino, fcnt, free].
 * This either works (return 0) or gets an EFSCORRUPTED error.
 */
int                                     /* error */
xfs_inobt_update(
        xfs_btree_cur_t         *cur,   /* btree cursor */
        xfs_agino_t             ino,    /* starting inode of chunk */
        __int32_t               fcnt,   /* free inode count */
        xfs_inofree_t           free)   /* free inode mask */
{
        xfs_inobt_block_t       *block; /* btree block to update */
        xfs_buf_t               *bp;    /* buffer containing btree block */
        int                     error;  /* error return value */
        int                     ptr;    /* current record number (updating) */
        xfs_inobt_rec_t         *rp;    /* pointer to updated record */

        /*
         * Pick up the current block.
         */
        bp = cur->bc_bufs[0];
        block = XFS_BUF_TO_INOBT_BLOCK(bp);
#ifdef DEBUG
        if ((error = xfs_btree_check_sblock(cur, block, 0, bp)))
                return error;
#endif
        /*
         * Get the address of the rec to be updated.
         */
        ptr = cur->bc_ptrs[0];
        rp = XFS_INOBT_REC_ADDR(block, ptr, cur);
        /*
         * Fill in the new contents and log them.
         */
        INT_SET(rp->ir_startino, ARCH_CONVERT, ino);
        INT_SET(rp->ir_freecount, ARCH_CONVERT, fcnt);
        INT_SET(rp->ir_free, ARCH_CONVERT, free);
        xfs_inobt_log_recs(cur, bp, ptr, ptr);
        /*
         * Updating first record in leaf. Pass new key value up to our parent.
         */
        if (ptr == 1) {
                xfs_inobt_key_t key;    /* key containing [ino] */

                INT_SET(key.ir_startino, ARCH_CONVERT, ino);
                if ((error = xfs_inobt_updkey(cur, &key, 1)))
                        return error;
        }
        return 0;
}