xfs_btree.c

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/*
 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * 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.
 *
 * 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.  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 the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_inode_item.h"
#include "xfs_btree.h"
#include "xfs_error.h"
#include "xfs_trace.h"

/*
 * Cursor allocation zone.
 */
kmem_zone_t *xfs_btree_cur_zone;

/*
 * Btree magic numbers.
 */
const __uint32_t xfs_magics[XFS_BTNUM_MAX] = {
    XFS_ABTB_MAGIC, XFS_ABTC_MAGIC, XFS_BMAP_MAGIC, XFS_IBT_MAGIC
};


STATIC int              /* error (0 or EFSCORRUPTED) */
xfs_btree_check_lblock(
    struct xfs_btree_cur    *cur,   /* btree cursor */
    struct xfs_btree_block  *block, /* btree long form block pointer */
    int         level,  /* level of the btree block */
    struct xfs_buf      *bp)    /* buffer for block, if any */
{
    int         lblock_ok; /* block passes checks */
    struct xfs_mount    *mp;    /* file system mount point */

    mp = cur->bc_mp;
    lblock_ok =
        be32_to_cpu(block->bb_magic) == xfs_magics[cur->bc_btnum] &&
        be16_to_cpu(block->bb_level) == level &&
        be16_to_cpu(block->bb_numrecs) <=
            cur->bc_ops->get_maxrecs(cur, level) &&
        block->bb_u.l.bb_leftsib &&
        (block->bb_u.l.bb_leftsib == cpu_to_be64(NULLDFSBNO) ||
         XFS_FSB_SANITY_CHECK(mp,
            be64_to_cpu(block->bb_u.l.bb_leftsib))) &&
        block->bb_u.l.bb_rightsib &&
        (block->bb_u.l.bb_rightsib == cpu_to_be64(NULLDFSBNO) ||
         XFS_FSB_SANITY_CHECK(mp,
            be64_to_cpu(block->bb_u.l.bb_rightsib)));
    if (unlikely(XFS_TEST_ERROR(!lblock_ok, mp,
            XFS_ERRTAG_BTREE_CHECK_LBLOCK,
            XFS_RANDOM_BTREE_CHECK_LBLOCK))) {
        if (bp)
            trace_xfs_btree_corrupt(bp, _RET_IP_);
        XFS_ERROR_REPORT("xfs_btree_check_lblock", XFS_ERRLEVEL_LOW,
                 mp);
        return XFS_ERROR(EFSCORRUPTED);
    }
    return 0;
}

STATIC int              /* error (0 or EFSCORRUPTED) */
xfs_btree_check_sblock(
    struct xfs_btree_cur    *cur,   /* btree cursor */
    struct xfs_btree_block  *block, /* btree short form block pointer */
    int         level,  /* level of the btree block */
    struct xfs_buf      *bp)    /* buffer containing block */
{
    struct xfs_buf      *agbp;  /* buffer for ag. freespace struct */
    struct xfs_agf      *agf;   /* ag. freespace structure */
    xfs_agblock_t       agflen; /* native ag. freespace length */
    int         sblock_ok; /* block passes checks */

    agbp = cur->bc_private.a.agbp;
    agf = XFS_BUF_TO_AGF(agbp);
    agflen = be32_to_cpu(agf->agf_length);
    sblock_ok =
        be32_to_cpu(block->bb_magic) == xfs_magics[cur->bc_btnum] &&
        be16_to_cpu(block->bb_level) == level &&
        be16_to_cpu(block->bb_numrecs) <=
            cur->bc_ops->get_maxrecs(cur, level) &&
        (block->bb_u.s.bb_leftsib == cpu_to_be32(NULLAGBLOCK) ||
         be32_to_cpu(block->bb_u.s.bb_leftsib) < agflen) &&
        block->bb_u.s.bb_leftsib &&
        (block->bb_u.s.bb_rightsib == cpu_to_be32(NULLAGBLOCK) ||
         be32_to_cpu(block->bb_u.s.bb_rightsib) < agflen) &&
        block->bb_u.s.bb_rightsib;
    if (unlikely(XFS_TEST_ERROR(!sblock_ok, cur->bc_mp,
            XFS_ERRTAG_BTREE_CHECK_SBLOCK,
            XFS_RANDOM_BTREE_CHECK_SBLOCK))) {
        if (bp)
            trace_xfs_btree_corrupt(bp, _RET_IP_);
        XFS_CORRUPTION_ERROR("xfs_btree_check_sblock",
            XFS_ERRLEVEL_LOW, cur->bc_mp, block);
        return XFS_ERROR(EFSCORRUPTED);
    }
    return 0;
}

/*
 * Debug routine: check that block header is ok.
 */
int
xfs_btree_check_block(
    struct xfs_btree_cur    *cur,   /* btree cursor */
    struct xfs_btree_block  *block, /* generic btree block pointer */
    int         level,  /* level of the btree block */
    struct xfs_buf      *bp)    /* buffer containing block, if any */
{
    if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
        return xfs_btree_check_lblock(cur, block, level, bp);
    else
        return xfs_btree_check_sblock(cur, block, level, bp);
}

/*
 * Check that (long) pointer is ok.
 */
int                 /* error (0 or EFSCORRUPTED) */
xfs_btree_check_lptr(
    struct xfs_btree_cur    *cur,   /* btree cursor */
    xfs_dfsbno_t        bno,    /* btree block disk address */
    int         level)  /* btree block level */
{
    XFS_WANT_CORRUPTED_RETURN(
        level > 0 &&
        bno != NULLDFSBNO &&
        XFS_FSB_SANITY_CHECK(cur->bc_mp, bno));
    return 0;
}

#ifdef DEBUG
/*
 * Check that (short) pointer is ok.
 */
STATIC int              /* error (0 or EFSCORRUPTED) */
xfs_btree_check_sptr(
    struct xfs_btree_cur    *cur,   /* btree cursor */
    xfs_agblock_t       bno,    /* btree block disk address */
    int         level)  /* btree block level */
{
    xfs_agblock_t       agblocks = cur->bc_mp->m_sb.sb_agblocks;

    XFS_WANT_CORRUPTED_RETURN(
        level > 0 &&
        bno != NULLAGBLOCK &&
        bno != 0 &&
        bno < agblocks);
    return 0;
}

/*
 * Check that block ptr is ok.
 */
STATIC int              /* error (0 or EFSCORRUPTED) */
xfs_btree_check_ptr(
    struct xfs_btree_cur    *cur,   /* btree cursor */
    union xfs_btree_ptr *ptr,   /* btree block disk address */
    int         index,  /* offset from ptr to check */
    int         level)  /* btree block level */
{
    if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
        return xfs_btree_check_lptr(cur,
                be64_to_cpu((&ptr->l)[index]), level);
    } else {
        return xfs_btree_check_sptr(cur,
                be32_to_cpu((&ptr->s)[index]), level);
    }
}
#endif

/*
 * Delete the btree cursor.
 */
void
xfs_btree_del_cursor(
    xfs_btree_cur_t *cur,       /* btree cursor */
    int     error)      /* del because of error */
{
    int     i;      /* btree level */

    /*
     * Clear the buffer pointers, and release the buffers.
     * If we're doing this in the face of an error, we
     * need to make sure to inspect all of the entries
     * in the bc_bufs array for buffers to be unlocked.
     * This is because some of the btree code works from
     * level n down to 0, and if we get an error along
     * the way we won't have initialized all the entries
     * down to 0.
     */
    for (i = 0; i < cur->bc_nlevels; i++) {
        if (cur->bc_bufs[i])
            xfs_trans_brelse(cur->bc_tp, cur->bc_bufs[i]);
        else if (!error)
            break;
    }
    /*
     * Can't free a bmap cursor without having dealt with the
     * allocated indirect blocks' accounting.
     */
    ASSERT(cur->bc_btnum != XFS_BTNUM_BMAP ||
           cur->bc_private.b.allocated == 0);
    /*
     * Free the cursor.
     */
    kmem_zone_free(xfs_btree_cur_zone, cur);
}

/*
 * Duplicate the btree cursor.
 * Allocate a new one, copy the record, re-get the buffers.
 */
int                 /* error */
xfs_btree_dup_cursor(
    xfs_btree_cur_t *cur,       /* input cursor */
    xfs_btree_cur_t **ncur)     /* output cursor */
{
    xfs_buf_t   *bp;        /* btree block's buffer pointer */
    int     error;      /* error return value */
    int     i;      /* level number of btree block */
    xfs_mount_t *mp;        /* mount structure for filesystem */
    xfs_btree_cur_t *new;       /* new cursor value */
    xfs_trans_t *tp;        /* transaction pointer, can be NULL */

    tp = cur->bc_tp;
    mp = cur->bc_mp;

    /*
     * Allocate a new cursor like the old one.
     */
    new = cur->bc_ops->dup_cursor(cur);

    /*
     * Copy the record currently in the cursor.
     */
    new->bc_rec = cur->bc_rec;

    /*
     * For each level current, re-get the buffer and copy the ptr value.
     */
    for (i = 0; i < new->bc_nlevels; i++) {
        new->bc_ptrs[i] = cur->bc_ptrs[i];
        new->bc_ra[i] = cur->bc_ra[i];
        if ((bp = cur->bc_bufs[i])) {
            if ((error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
                XFS_BUF_ADDR(bp), mp->m_bsize, 0, &bp))) {
                xfs_btree_del_cursor(new, error);
                *ncur = NULL;
                return error;
            }
            new->bc_bufs[i] = bp;
            ASSERT(!xfs_buf_geterror(bp));
        } else
            new->bc_bufs[i] = NULL;
    }
    *ncur = new;
    return 0;
}

/*
 * XFS btree block layout and addressing:
 *
 * There are two types of blocks in the btree: leaf and non-leaf blocks.
 *
 * The leaf record start with a header then followed by records containing
 * the values.  A non-leaf block also starts with the same header, and
 * then first contains lookup keys followed by an equal number of pointers
 * to the btree blocks at the previous level.
 *
 *      +--------+-------+-------+-------+-------+-------+-------+
 * Leaf:    | header | rec 1 | rec 2 | rec 3 | rec 4 | rec 5 | rec N |
 *      +--------+-------+-------+-------+-------+-------+-------+
 *
 *      +--------+-------+-------+-------+-------+-------+-------+
 * Non-Leaf:    | header | key 1 | key 2 | key N | ptr 1 | ptr 2 | ptr N |
 *      +--------+-------+-------+-------+-------+-------+-------+
 *
 * The header is called struct xfs_btree_block for reasons better left unknown
 * and comes in different versions for short (32bit) and long (64bit) block
 * pointers.  The record and key structures are defined by the btree instances
 * and opaque to the btree core.  The block pointers are simple disk endian
 * integers, available in a short (32bit) and long (64bit) variant.
 *
 * The helpers below calculate the offset of a given record, key or pointer
 * into a btree block (xfs_btree_*_offset) or return a pointer to the given
 * record, key or pointer (xfs_btree_*_addr).  Note that all addressing
 * inside the btree block is done using indices starting at one, not zero!
 */

/*
 * Return size of the btree block header for this btree instance.
 */
static inline size_t xfs_btree_block_len(struct xfs_btree_cur *cur)
{
    return (cur->bc_flags & XFS_BTREE_LONG_PTRS) ?
        XFS_BTREE_LBLOCK_LEN :
        XFS_BTREE_SBLOCK_LEN;
}

/*
 * Return size of btree block pointers for this btree instance.
 */
static inline size_t xfs_btree_ptr_len(struct xfs_btree_cur *cur)
{
    return (cur->bc_flags & XFS_BTREE_LONG_PTRS) ?
        sizeof(__be64) : sizeof(__be32);
}

/*
 * Calculate offset of the n-th record in a btree block.
 */
STATIC size_t
xfs_btree_rec_offset(
    struct xfs_btree_cur    *cur,
    int         n)
{
    return xfs_btree_block_len(cur) +
        (n - 1) * cur->bc_ops->rec_len;
}

/*
 * Calculate offset of the n-th key in a btree block.
 */
STATIC size_t
xfs_btree_key_offset(
    struct xfs_btree_cur    *cur,
    int         n)
{
    return xfs_btree_block_len(cur) +
        (n - 1) * cur->bc_ops->key_len;
}

/*
 * Calculate offset of the n-th block pointer in a btree block.
 */
STATIC size_t
xfs_btree_ptr_offset(
    struct xfs_btree_cur    *cur,
    int         n,
    int         level)
{
    return xfs_btree_block_len(cur) +
        cur->bc_ops->get_maxrecs(cur, level) * cur->bc_ops->key_len +
        (n - 1) * xfs_btree_ptr_len(cur);
}

/*
 * Return a pointer to the n-th record in the btree block.
 */
STATIC union xfs_btree_rec *
xfs_btree_rec_addr(
    struct xfs_btree_cur    *cur,
    int         n,
    struct xfs_btree_block  *block)
{
    return (union xfs_btree_rec *)
        ((char *)block + xfs_btree_rec_offset(cur, n));
}

/*
 * Return a pointer to the n-th key in the btree block.
 */
STATIC union xfs_btree_key *
xfs_btree_key_addr(
    struct xfs_btree_cur    *cur,
    int         n,
    struct xfs_btree_block  *block)
{
    return (union xfs_btree_key *)
        ((char *)block + xfs_btree_key_offset(cur, n));
}

/*
 * Return a pointer to the n-th block pointer in the btree block.
 */
STATIC union xfs_btree_ptr *
xfs_btree_ptr_addr(
    struct xfs_btree_cur    *cur,
    int         n,
    struct xfs_btree_block  *block)
{
    int         level = xfs_btree_get_level(block);

    ASSERT(block->bb_level != 0);

    return (union xfs_btree_ptr *)
        ((char *)block + xfs_btree_ptr_offset(cur, n, level));
}

/*
 * Get a the root block which is stored in the inode.
 *
 * For now this btree implementation assumes the btree root is always
 * stored in the if_broot field of an inode fork.
 */
STATIC struct xfs_btree_block *
xfs_btree_get_iroot(
       struct xfs_btree_cur    *cur)
{
       struct xfs_ifork        *ifp;

       ifp = XFS_IFORK_PTR(cur->bc_private.b.ip, cur->bc_private.b.whichfork);
       return (struct xfs_btree_block *)ifp->if_broot;
}

/*
 * Retrieve the block pointer from the cursor at the given level.
 * This may be an inode btree root or from a buffer.
 */
STATIC struct xfs_btree_block *     /* generic btree block pointer */
xfs_btree_get_block(
    struct xfs_btree_cur    *cur,   /* btree cursor */
    int         level,  /* level in btree */
    struct xfs_buf      **bpp)  /* buffer containing the block */
{
    if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
        (level == cur->bc_nlevels - 1)) {
        *bpp = NULL;
        return xfs_btree_get_iroot(cur);
    }

    *bpp = cur->bc_bufs[level];
    return XFS_BUF_TO_BLOCK(*bpp);
}

/*
 * Get a buffer for the block, return it with no data read.
 * Long-form addressing.
 */
xfs_buf_t *             /* buffer for fsbno */
xfs_btree_get_bufl(
    xfs_mount_t *mp,        /* file system mount point */
    xfs_trans_t *tp,        /* transaction pointer */
    xfs_fsblock_t   fsbno,      /* file system block number */
    uint        lock)       /* lock flags for get_buf */
{
    xfs_buf_t   *bp;        /* buffer pointer (return value) */
    xfs_daddr_t     d;      /* real disk block address */

    ASSERT(fsbno != NULLFSBLOCK);
    d = XFS_FSB_TO_DADDR(mp, fsbno);
    bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d, mp->m_bsize, lock);
    ASSERT(!xfs_buf_geterror(bp));
    return bp;
}

/*
 * Get a buffer for the block, return it with no data read.
 * Short-form addressing.
 */
xfs_buf_t *             /* buffer for agno/agbno */
xfs_btree_get_bufs(
    xfs_mount_t *mp,        /* file system mount point */
    xfs_trans_t *tp,        /* transaction pointer */
    xfs_agnumber_t  agno,       /* allocation group number */
    xfs_agblock_t   agbno,      /* allocation group block number */
    uint        lock)       /* lock flags for get_buf */
{
    xfs_buf_t   *bp;        /* buffer pointer (return value) */
    xfs_daddr_t     d;      /* real disk block address */

    ASSERT(agno != NULLAGNUMBER);
    ASSERT(agbno != NULLAGBLOCK);
    d = XFS_AGB_TO_DADDR(mp, agno, agbno);
    bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d, mp->m_bsize, lock);
    ASSERT(!xfs_buf_geterror(bp));
    return bp;
}

/*
 * Check for the cursor referring to the last block at the given level.
 */
int                 /* 1=is last block, 0=not last block */
xfs_btree_islastblock(
    xfs_btree_cur_t     *cur,   /* btree cursor */
    int         level)  /* level to check */
{
    struct xfs_btree_block  *block; /* generic btree block pointer */
    xfs_buf_t       *bp;    /* buffer containing block */

    block = xfs_btree_get_block(cur, level, &bp);
    xfs_btree_check_block(cur, block, level, bp);
    if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
        return block->bb_u.l.bb_rightsib == cpu_to_be64(NULLDFSBNO);
    else
        return block->bb_u.s.bb_rightsib == cpu_to_be32(NULLAGBLOCK);
}

/*
 * Change the cursor to point to the first record at the given level.
 * Other levels are unaffected.
 */
STATIC int              /* success=1, failure=0 */
xfs_btree_firstrec(
    xfs_btree_cur_t     *cur,   /* btree cursor */
    int         level)  /* level to change */
{
    struct xfs_btree_block  *block; /* generic btree block pointer */
    xfs_buf_t       *bp;    /* buffer containing block */

    /*
     * Get the block pointer for this level.
     */
    block = xfs_btree_get_block(cur, level, &bp);
    xfs_btree_check_block(cur, block, level, bp);
    /*
     * It's empty, there is no such record.
     */
    if (!block->bb_numrecs)
        return 0;
    /*
     * Set the ptr value to 1, that's the first record/key.
     */
    cur->bc_ptrs[level] = 1;
    return 1;
}

/*
 * Change the cursor to point to the last record in the current block
 * at the given level.  Other levels are unaffected.
 */
STATIC int              /* success=1, failure=0 */
xfs_btree_lastrec(
    xfs_btree_cur_t     *cur,   /* btree cursor */
    int         level)  /* level to change */
{
    struct xfs_btree_block  *block; /* generic btree block pointer */
    xfs_buf_t       *bp;    /* buffer containing block */

    /*
     * Get the block pointer for this level.
     */
    block = xfs_btree_get_block(cur, level, &bp);
    xfs_btree_check_block(cur, block, level, bp);
    /*
     * It's empty, there is no such record.
     */
    if (!block->bb_numrecs)
        return 0;
    /*
     * Set the ptr value to numrecs, that's the last record/key.
     */
    cur->bc_ptrs[level] = be16_to_cpu(block->bb_numrecs);
    return 1;
}

/*
 * Compute first and last byte offsets for the fields given.
 * Interprets the offsets table, which contains struct field offsets.
 */
void
xfs_btree_offsets(
    __int64_t   fields,     /* bitmask of fields */
    const short *offsets,   /* table of field offsets */
    int     nbits,      /* number of bits to inspect */
    int     *first,     /* output: first byte offset */
    int     *last)      /* output: last byte offset */
{
    int     i;      /* current bit number */
    __int64_t   imask;      /* mask for current bit number */

    ASSERT(fields != 0);
    /*
     * Find the lowest bit, so the first byte offset.
     */
    for (i = 0, imask = 1LL; ; i++, imask <<= 1) {
        if (imask & fields) {
            *first = offsets[i];
            break;
        }
    }
    /*
     * Find the highest bit, so the last byte offset.
     */
    for (i = nbits - 1, imask = 1LL << i; ; i--, imask >>= 1) {
        if (imask & fields) {
            *last = offsets[i + 1] - 1;
            break;
        }
    }
}

/*
 * Get a buffer for the block, return it read in.
 * Long-form addressing.
 */
int                 /* error */
xfs_btree_read_bufl(
    xfs_mount_t *mp,        /* file system mount point */
    xfs_trans_t *tp,        /* transaction pointer */
    xfs_fsblock_t   fsbno,      /* file system block number */
    uint        lock,       /* lock flags for read_buf */
    xfs_buf_t   **bpp,      /* buffer for fsbno */
    int     refval)     /* ref count value for buffer */
{
    xfs_buf_t   *bp;        /* return value */
    xfs_daddr_t     d;      /* real disk block address */
    int     error;

    ASSERT(fsbno != NULLFSBLOCK);
    d = XFS_FSB_TO_DADDR(mp, fsbno);
    if ((error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, d,
            mp->m_bsize, lock, &bp))) {
        return error;
    }
    ASSERT(!xfs_buf_geterror(bp));
    if (bp)
        xfs_buf_set_ref(bp, refval);
    *bpp = bp;
    return 0;
}

/*
 * Read-ahead the block, don't wait for it, don't return a buffer.
 * Long-form addressing.
 */
/* ARGSUSED */
void
xfs_btree_reada_bufl(
    xfs_mount_t *mp,        /* file system mount point */
    xfs_fsblock_t   fsbno,      /* file system block number */
    xfs_extlen_t    count)      /* count of filesystem blocks */
{
    xfs_daddr_t     d;

    ASSERT(fsbno != NULLFSBLOCK);
    d = XFS_FSB_TO_DADDR(mp, fsbno);
    xfs_buf_readahead(mp->m_ddev_targp, d, mp->m_bsize * count);
}

/*
 * Read-ahead the block, don't wait for it, don't return a buffer.
 * Short-form addressing.
 */
/* ARGSUSED */
void
xfs_btree_reada_bufs(
    xfs_mount_t *mp,        /* file system mount point */
    xfs_agnumber_t  agno,       /* allocation group number */
    xfs_agblock_t   agbno,      /* allocation group block number */
    xfs_extlen_t    count)      /* count of filesystem blocks */
{
    xfs_daddr_t     d;

    ASSERT(agno != NULLAGNUMBER);
    ASSERT(agbno != NULLAGBLOCK);
    d = XFS_AGB_TO_DADDR(mp, agno, agbno);
    xfs_buf_readahead(mp->m_ddev_targp, d, mp->m_bsize * count);
}

STATIC int
xfs_btree_readahead_lblock(
    struct xfs_btree_cur    *cur,
    int         lr,
    struct xfs_btree_block  *block)
{
    int         rval = 0;
    xfs_dfsbno_t        left = be64_to_cpu(block->bb_u.l.bb_leftsib);
    xfs_dfsbno_t        right = be64_to_cpu(block->bb_u.l.bb_rightsib);

    if ((lr & XFS_BTCUR_LEFTRA) && left != NULLDFSBNO) {
        xfs_btree_reada_bufl(cur->bc_mp, left, 1);
        rval++;
    }

    if ((lr & XFS_BTCUR_RIGHTRA) && right != NULLDFSBNO) {
        xfs_btree_reada_bufl(cur->bc_mp, right, 1);
        rval++;
    }

    return rval;
}

STATIC int
xfs_btree_readahead_sblock(
    struct xfs_btree_cur    *cur,
    int         lr,
    struct xfs_btree_block *block)
{
    int         rval = 0;
    xfs_agblock_t       left = be32_to_cpu(block->bb_u.s.bb_leftsib);
    xfs_agblock_t       right = be32_to_cpu(block->bb_u.s.bb_rightsib);


    if ((lr & XFS_BTCUR_LEFTRA) && left != NULLAGBLOCK) {
        xfs_btree_reada_bufs(cur->bc_mp, cur->bc_private.a.agno,
                     left, 1);
        rval++;
    }

    if ((lr & XFS_BTCUR_RIGHTRA) && right != NULLAGBLOCK) {
        xfs_btree_reada_bufs(cur->bc_mp, cur->bc_private.a.agno,
                     right, 1);
        rval++;
    }

    return rval;
}

/*
 * Read-ahead btree blocks, at the given level.
 * Bits in lr are set from XFS_BTCUR_{LEFT,RIGHT}RA.
 */
STATIC int
xfs_btree_readahead(
    struct xfs_btree_cur    *cur,       /* btree cursor */
    int         lev,        /* level in btree */
    int         lr)     /* left/right bits */
{
    struct xfs_btree_block  *block;

    /*
     * No readahead needed if we are at the root level and the
     * btree root is stored in the inode.
     */
    if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
        (lev == cur->bc_nlevels - 1))
        return 0;

    if ((cur->bc_ra[lev] | lr) == cur->bc_ra[lev])
        return 0;

    cur->bc_ra[lev] |= lr;
    block = XFS_BUF_TO_BLOCK(cur->bc_bufs[lev]);

    if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
        return xfs_btree_readahead_lblock(cur, lr, block);
    return xfs_btree_readahead_sblock(cur, lr, block);
}

/*
 * Set the buffer for level "lev" in the cursor to bp, releasing
 * any previous buffer.
 */
STATIC void
xfs_btree_setbuf(
    xfs_btree_cur_t     *cur,   /* btree cursor */
    int         lev,    /* level in btree */
    xfs_buf_t       *bp)    /* new buffer to set */
{
    struct xfs_btree_block  *b; /* btree block */

    if (cur->bc_bufs[lev])
        xfs_trans_brelse(cur->bc_tp, cur->bc_bufs[lev]);
    cur->bc_bufs[lev] = bp;
    cur->bc_ra[lev] = 0;

    b = XFS_BUF_TO_BLOCK(bp);
    if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
        if (b->bb_u.l.bb_leftsib == cpu_to_be64(NULLDFSBNO))
            cur->bc_ra[lev] |= XFS_BTCUR_LEFTRA;
        if (b->bb_u.l.bb_rightsib == cpu_to_be64(NULLDFSBNO))
            cur->bc_ra[lev] |= XFS_BTCUR_RIGHTRA;
    } else {
        if (b->bb_u.s.bb_leftsib == cpu_to_be32(NULLAGBLOCK))
            cur->bc_ra[lev] |= XFS_BTCUR_LEFTRA;
        if (b->bb_u.s.bb_rightsib == cpu_to_be32(NULLAGBLOCK))
            cur->bc_ra[lev] |= XFS_BTCUR_RIGHTRA;
    }
}

STATIC int
xfs_btree_ptr_is_null(
    struct xfs_btree_cur    *cur,
    union xfs_btree_ptr *ptr)
{
    if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
        return ptr->l == cpu_to_be64(NULLDFSBNO);
    else
        return ptr->s == cpu_to_be32(NULLAGBLOCK);
}

STATIC void
xfs_btree_set_ptr_null(
    struct xfs_btree_cur    *cur,
    union xfs_btree_ptr *ptr)
{
    if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
        ptr->l = cpu_to_be64(NULLDFSBNO);
    else
        ptr->s = cpu_to_be32(NULLAGBLOCK);
}

/*
 * Get/set/init sibling pointers
 */
STATIC void
xfs_btree_get_sibling(
    struct xfs_btree_cur    *cur,
    struct xfs_btree_block  *block,
    union xfs_btree_ptr *ptr,
    int         lr)
{
    ASSERT(lr == XFS_BB_LEFTSIB || lr == XFS_BB_RIGHTSIB);

    if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
        if (lr == XFS_BB_RIGHTSIB)
            ptr->l = block->bb_u.l.bb_rightsib;
        else
            ptr->l = block->bb_u.l.bb_leftsib;
    } else {
        if (lr == XFS_BB_RIGHTSIB)
            ptr->s = block->bb_u.s.bb_rightsib;
        else
            ptr->s = block->bb_u.s.bb_leftsib;
    }
}

STATIC void
xfs_btree_set_sibling(
    struct xfs_btree_cur    *cur,
    struct xfs_btree_block  *block,
    union xfs_btree_ptr *ptr,
    int         lr)
{
    ASSERT(lr == XFS_BB_LEFTSIB || lr == XFS_BB_RIGHTSIB);

    if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
        if (lr == XFS_BB_RIGHTSIB)
            block->bb_u.l.bb_rightsib = ptr->l;
        else
            block->bb_u.l.bb_leftsib = ptr->l;
    } else {
        if (lr == XFS_BB_RIGHTSIB)
            block->bb_u.s.bb_rightsib = ptr->s;
        else
            block->bb_u.s.bb_leftsib = ptr->s;
    }
}

STATIC void
xfs_btree_init_block(
    struct xfs_btree_cur    *cur,
    int         level,
    int         numrecs,
    struct xfs_btree_block  *new)   /* new block */
{
    new->bb_magic = cpu_to_be32(xfs_magics[cur->bc_btnum]);
    new->bb_level = cpu_to_be16(level);
    new->bb_numrecs = cpu_to_be16(numrecs);

    if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
        new->bb_u.l.bb_leftsib = cpu_to_be64(NULLDFSBNO);
        new->bb_u.l.bb_rightsib = cpu_to_be64(NULLDFSBNO);
    } else {
        new->bb_u.s.bb_leftsib = cpu_to_be32(NULLAGBLOCK);
        new->bb_u.s.bb_rightsib = cpu_to_be32(NULLAGBLOCK);
    }
}

/*
 * Return true if ptr is the last record in the btree and
 * we need to track updateѕ to this record.  The decision
 * will be further refined in the update_lastrec method.
 */
STATIC int
xfs_btree_is_lastrec(
    struct xfs_btree_cur    *cur,
    struct xfs_btree_block  *block,
    int         level)
{
    union xfs_btree_ptr ptr;

    if (level > 0)
        return 0;
    if (!(cur->bc_flags & XFS_BTREE_LASTREC_UPDATE))
        return 0;

    xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_RIGHTSIB);
    if (!xfs_btree_ptr_is_null(cur, &ptr))
        return 0;
    return 1;
}

STATIC void
xfs_btree_buf_to_ptr(
    struct xfs_btree_cur    *cur,
    struct xfs_buf      *bp,
    union xfs_btree_ptr *ptr)
{
    if (cur->bc_flags & XFS_BTREE_LONG_PTRS)
        ptr->l = cpu_to_be64(XFS_DADDR_TO_FSB(cur->bc_mp,
                    XFS_BUF_ADDR(bp)));
    else {
        ptr->s = cpu_to_be32(xfs_daddr_to_agbno(cur->bc_mp,
                    XFS_BUF_ADDR(bp)));
    }
}

STATIC xfs_daddr_t
xfs_btree_ptr_to_daddr(
    struct xfs_btree_cur    *cur,
    union xfs_btree_ptr *ptr)
{
    if (cur->bc_flags & XFS_BTREE_LONG_PTRS) {
        ASSERT(ptr->l != cpu_to_be64(NULLDFSBNO));

        return XFS_FSB_TO_DADDR(cur->bc_mp, be64_to_cpu(ptr->l));
    } else {
        ASSERT(cur->bc_private.a.agno != NULLAGNUMBER);
        ASSERT(ptr->s != cpu_to_be32(NULLAGBLOCK));

        return XFS_AGB_TO_DADDR(cur->bc_mp, cur->bc_private.a.agno,
                    be32_to_cpu(ptr->s));
    }
}

STATIC void
xfs_btree_set_refs(
    struct xfs_btree_cur    *cur,
    struct xfs_buf      *bp)
{
    switch (cur->bc_btnum) {
    case XFS_BTNUM_BNO:
    case XFS_BTNUM_CNT:
        xfs_buf_set_ref(bp, XFS_ALLOC_BTREE_REF);
        break;
    case XFS_BTNUM_INO:
        xfs_buf_set_ref(bp, XFS_INO_BTREE_REF);
        break;
    case XFS_BTNUM_BMAP:
        xfs_buf_set_ref(bp, XFS_BMAP_BTREE_REF);
        break;
    default:
        ASSERT(0);
    }
}

STATIC int
xfs_btree_get_buf_block(
    struct xfs_btree_cur    *cur,
    union xfs_btree_ptr *ptr,
    int         flags,
    struct xfs_btree_block  **block,
    struct xfs_buf      **bpp)
{
    struct xfs_mount    *mp = cur->bc_mp;
    xfs_daddr_t     d;

    /* need to sort out how callers deal with failures first */
    ASSERT(!(flags & XBF_TRYLOCK));

    d = xfs_btree_ptr_to_daddr(cur, ptr);
    *bpp = xfs_trans_get_buf(cur->bc_tp, mp->m_ddev_targp, d,
                 mp->m_bsize, flags);

    if (!*bpp)
        return ENOMEM;

    *block = XFS_BUF_TO_BLOCK(*bpp);
    return 0;
}

/*
 * Read in the buffer at the given ptr and return the buffer and
 * the block pointer within the buffer.
 */
STATIC int
xfs_btree_read_buf_block(
    struct xfs_btree_cur    *cur,
    union xfs_btree_ptr *ptr,
    int         level,
    int         flags,
    struct xfs_btree_block  **block,
    struct xfs_buf      **bpp)
{
    struct xfs_mount    *mp = cur->bc_mp;
    xfs_daddr_t     d;
    int         error;

    /* need to sort out how callers deal with failures first */
    ASSERT(!(flags & XBF_TRYLOCK));

    d = xfs_btree_ptr_to_daddr(cur, ptr);
    error = xfs_trans_read_buf(mp, cur->bc_tp, mp->m_ddev_targp, d,
                   mp->m_bsize, flags, bpp);
    if (error)
        return error;

    ASSERT(!xfs_buf_geterror(*bpp));

    xfs_btree_set_refs(cur, *bpp);
    *block = XFS_BUF_TO_BLOCK(*bpp);

    error = xfs_btree_check_block(cur, *block, level, *bpp);
    if (error)
        xfs_trans_brelse(cur->bc_tp, *bpp);
    return error;
}

/*
 * Copy keys from one btree block to another.
 */
STATIC void
xfs_btree_copy_keys(
    struct xfs_btree_cur    *cur,
    union xfs_btree_key *dst_key,
    union xfs_btree_key *src_key,
    int         numkeys)
{
    ASSERT(numkeys >= 0);
    memcpy(dst_key, src_key, numkeys * cur->bc_ops->key_len);
}

/*
 * Copy records from one btree block to another.
 */
STATIC void
xfs_btree_copy_recs(
    struct xfs_btree_cur    *cur,
    union xfs_btree_rec *dst_rec,
    union xfs_btree_rec *src_rec,
    int         numrecs)
{
    ASSERT(numrecs >= 0);
    memcpy(dst_rec, src_rec, numrecs * cur->bc_ops->rec_len);
}

/*
 * Copy block pointers from one btree block to another.
 */
STATIC void
xfs_btree_copy_ptrs(
    struct xfs_btree_cur    *cur,
    union xfs_btree_ptr *dst_ptr,
    union xfs_btree_ptr *src_ptr,
    int         numptrs)
{
    ASSERT(numptrs >= 0);
    memcpy(dst_ptr, src_ptr, numptrs * xfs_btree_ptr_len(cur));
}

/*
 * Shift keys one index left/right inside a single btree block.
 */
STATIC void
xfs_btree_shift_keys(
    struct xfs_btree_cur    *cur,
    union xfs_btree_key *key,
    int         dir,
    int         numkeys)
{
    char            *dst_key;

    ASSERT(numkeys >= 0);
    ASSERT(dir == 1 || dir == -1);

    dst_key = (char *)key + (dir * cur->bc_ops->key_len);
    memmove(dst_key, key, numkeys * cur->bc_ops->key_len);
}

/*
 * Shift records one index left/right inside a single btree block.
 */
STATIC void
xfs_btree_shift_recs(
    struct xfs_btree_cur    *cur,
    union xfs_btree_rec *rec,
    int         dir,
    int         numrecs)
{
    char            *dst_rec;

    ASSERT(numrecs >= 0);
    ASSERT(dir == 1 || dir == -1);

    dst_rec = (char *)rec + (dir * cur->bc_ops->rec_len);
    memmove(dst_rec, rec, numrecs * cur->bc_ops->rec_len);
}

/*
 * Shift block pointers one index left/right inside a single btree block.
 */
STATIC void
xfs_btree_shift_ptrs(
    struct xfs_btree_cur    *cur,
    union xfs_btree_ptr *ptr,
    int         dir,
    int         numptrs)
{
    char            *dst_ptr;

    ASSERT(numptrs >= 0);
    ASSERT(dir == 1 || dir == -1);

    dst_ptr = (char *)ptr + (dir * xfs_btree_ptr_len(cur));
    memmove(dst_ptr, ptr, numptrs * xfs_btree_ptr_len(cur));
}

/*
 * Log key values from the btree block.
 */
STATIC void
xfs_btree_log_keys(
    struct xfs_btree_cur    *cur,
    struct xfs_buf      *bp,
    int         first,
    int         last)
{
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_TRACE_ARGBII(cur, bp, first, last);

    if (bp) {
        xfs_trans_log_buf(cur->bc_tp, bp,
                  xfs_btree_key_offset(cur, first),
                  xfs_btree_key_offset(cur, last + 1) - 1);
    } else {
        xfs_trans_log_inode(cur->bc_tp, cur->bc_private.b.ip,
                xfs_ilog_fbroot(cur->bc_private.b.whichfork));
    }

    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
}

/*
 * Log record values from the btree block.
 */
void
xfs_btree_log_recs(
    struct xfs_btree_cur    *cur,
    struct xfs_buf      *bp,
    int         first,
    int         last)
{
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_TRACE_ARGBII(cur, bp, first, last);

    xfs_trans_log_buf(cur->bc_tp, bp,
              xfs_btree_rec_offset(cur, first),
              xfs_btree_rec_offset(cur, last + 1) - 1);

    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
}

/*
 * Log block pointer fields from a btree block (nonleaf).
 */
STATIC void
xfs_btree_log_ptrs(
    struct xfs_btree_cur    *cur,   /* btree cursor */
    struct xfs_buf      *bp,    /* buffer containing btree block */
    int         first,  /* index of first pointer to log */
    int         last)   /* index of last pointer to log */
{
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_TRACE_ARGBII(cur, bp, first, last);

    if (bp) {
        struct xfs_btree_block  *block = XFS_BUF_TO_BLOCK(bp);
        int         level = xfs_btree_get_level(block);

        xfs_trans_log_buf(cur->bc_tp, bp,
                xfs_btree_ptr_offset(cur, first, level),
                xfs_btree_ptr_offset(cur, last + 1, level) - 1);
    } else {
        xfs_trans_log_inode(cur->bc_tp, cur->bc_private.b.ip,
            xfs_ilog_fbroot(cur->bc_private.b.whichfork));
    }

    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
}

/*
 * Log fields from a btree block header.
 */
void
xfs_btree_log_block(
    struct xfs_btree_cur    *cur,   /* btree cursor */
    struct xfs_buf      *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  soffsets[] = {  /* table of offsets (short) */
        offsetof(struct xfs_btree_block, bb_magic),
        offsetof(struct xfs_btree_block, bb_level),
        offsetof(struct xfs_btree_block, bb_numrecs),
        offsetof(struct xfs_btree_block, bb_u.s.bb_leftsib),
        offsetof(struct xfs_btree_block, bb_u.s.bb_rightsib),
        XFS_BTREE_SBLOCK_LEN
    };
    static const short  loffsets[] = {  /* table of offsets (long) */
        offsetof(struct xfs_btree_block, bb_magic),
        offsetof(struct xfs_btree_block, bb_level),
        offsetof(struct xfs_btree_block, bb_numrecs),
        offsetof(struct xfs_btree_block, bb_u.l.bb_leftsib),
        offsetof(struct xfs_btree_block, bb_u.l.bb_rightsib),
        XFS_BTREE_LBLOCK_LEN
    };

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_TRACE_ARGBI(cur, bp, fields);

    if (bp) {
        xfs_btree_offsets(fields,
                  (cur->bc_flags & XFS_BTREE_LONG_PTRS) ?
                    loffsets : soffsets,
                  XFS_BB_NUM_BITS, &first, &last);
        xfs_trans_log_buf(cur->bc_tp, bp, first, last);
    } else {
        xfs_trans_log_inode(cur->bc_tp, cur->bc_private.b.ip,
            xfs_ilog_fbroot(cur->bc_private.b.whichfork));
    }

    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
}

/*
 * Increment cursor by one record at the level.
 * For nonzero levels the leaf-ward information is untouched.
 */
int                     /* error */
xfs_btree_increment(
    struct xfs_btree_cur    *cur,
    int         level,
    int         *stat)      /* success/failure */
{
    struct xfs_btree_block  *block;
    union xfs_btree_ptr ptr;
    struct xfs_buf      *bp;
    int         error;      /* error return value */
    int         lev;

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_TRACE_ARGI(cur, 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. */
    block = xfs_btree_get_block(cur, level, &bp);

#ifdef DEBUG
    error = xfs_btree_check_block(cur, block, level, bp);
    if (error)
        goto error0;
#endif

    /* We're done if we remain in the block after the increment. */
    if (++cur->bc_ptrs[level] <= xfs_btree_get_numrecs(block))
        goto out1;

    /* Fail if we just went off the right edge of the tree. */
    xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_RIGHTSIB);
    if (xfs_btree_ptr_is_null(cur, &ptr))
        goto out0;

    XFS_BTREE_STATS_INC(cur, increment);

    /*
     * 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++) {
        block = xfs_btree_get_block(cur, lev, &bp);

#ifdef DEBUG
        error = xfs_btree_check_block(cur, block, lev, bp);
        if (error)
            goto error0;
#endif

        if (++cur->bc_ptrs[lev] <= xfs_btree_get_numrecs(block))
            break;

        /* Read-ahead the right block for the next loop. */
        xfs_btree_readahead(cur, lev, XFS_BTCUR_RIGHTRA);
    }

    /*
     * If we went off the root then we are either seriously
     * confused or have the tree root in an inode.
     */
    if (lev == cur->bc_nlevels) {
        if (cur->bc_flags & XFS_BTREE_ROOT_IN_INODE)
            goto out0;
        ASSERT(0);
        error = EFSCORRUPTED;
        goto error0;
    }
    ASSERT(lev < cur->bc_nlevels);

    /*
     * Now walk back down the tree, fixing up the cursor's buffer
     * pointers and key numbers.
     */
    for (block = xfs_btree_get_block(cur, lev, &bp); lev > level; ) {
        union xfs_btree_ptr *ptrp;

        ptrp = xfs_btree_ptr_addr(cur, cur->bc_ptrs[lev], block);
        error = xfs_btree_read_buf_block(cur, ptrp, --lev,
                            0, &block, &bp);
        if (error)
            goto error0;

        xfs_btree_setbuf(cur, lev, bp);
        cur->bc_ptrs[lev] = 1;
    }
out1:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = 1;
    return 0;

out0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = 0;
    return 0;

error0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
    return error;
}

/*
 * Decrement cursor by one record at the level.
 * For nonzero levels the leaf-ward information is untouched.
 */
int                     /* error */
xfs_btree_decrement(
    struct xfs_btree_cur    *cur,
    int         level,
    int         *stat)      /* success/failure */
{
    struct xfs_btree_block  *block;
    xfs_buf_t       *bp;
    int         error;      /* error return value */
    int         lev;
    union xfs_btree_ptr ptr;

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_TRACE_ARGI(cur, level);

    ASSERT(level < cur->bc_nlevels);

    /* Read-ahead to the left at this level. */
    xfs_btree_readahead(cur, level, XFS_BTCUR_LEFTRA);

    /* We're done if we remain in the block after the decrement. */
    if (--cur->bc_ptrs[level] > 0)
        goto out1;

    /* Get a pointer to the btree block. */
    block = xfs_btree_get_block(cur, level, &bp);

#ifdef DEBUG
    error = xfs_btree_check_block(cur, block, level, bp);
    if (error)
        goto error0;
#endif

    /* Fail if we just went off the left edge of the tree. */
    xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_LEFTSIB);
    if (xfs_btree_ptr_is_null(cur, &ptr))
        goto out0;

    XFS_BTREE_STATS_INC(cur, decrement);

    /*
     * 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 for the next loop. */
        xfs_btree_readahead(cur, lev, XFS_BTCUR_LEFTRA);
    }

    /*
     * If we went off the root then we are seriously confused.
     * or the root of the tree is in an inode.
     */
    if (lev == cur->bc_nlevels) {
        if (cur->bc_flags & XFS_BTREE_ROOT_IN_INODE)
            goto out0;
        ASSERT(0);
        error = EFSCORRUPTED;
        goto error0;
    }
    ASSERT(lev < cur->bc_nlevels);

    /*
     * Now walk back down the tree, fixing up the cursor's buffer
     * pointers and key numbers.
     */
    for (block = xfs_btree_get_block(cur, lev, &bp); lev > level; ) {
        union xfs_btree_ptr *ptrp;

        ptrp = xfs_btree_ptr_addr(cur, cur->bc_ptrs[lev], block);
        error = xfs_btree_read_buf_block(cur, ptrp, --lev,
                            0, &block, &bp);
        if (error)
            goto error0;
        xfs_btree_setbuf(cur, lev, bp);
        cur->bc_ptrs[lev] = xfs_btree_get_numrecs(block);
    }
out1:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = 1;
    return 0;

out0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = 0;
    return 0;

error0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
    return error;
}

STATIC int
xfs_btree_lookup_get_block(
    struct xfs_btree_cur    *cur,   /* btree cursor */
    int         level,  /* level in the btree */
    union xfs_btree_ptr *pp,    /* ptr to btree block */
    struct xfs_btree_block  **blkp) /* return btree block */
{
    struct xfs_buf      *bp;    /* buffer pointer for btree block */
    int         error = 0;

    /* special case the root block if in an inode */
    if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
        (level == cur->bc_nlevels - 1)) {
        *blkp = xfs_btree_get_iroot(cur);
        return 0;
    }

    /*
     * If the old buffer at this level for the disk address we are
     * looking for re-use it.
     *
     * Otherwise throw it away and get a new one.
     */
    bp = cur->bc_bufs[level];
    if (bp && XFS_BUF_ADDR(bp) == xfs_btree_ptr_to_daddr(cur, pp)) {
        *blkp = XFS_BUF_TO_BLOCK(bp);
        return 0;
    }

    error = xfs_btree_read_buf_block(cur, pp, level, 0, blkp, &bp);
    if (error)
        return error;

    xfs_btree_setbuf(cur, level, bp);
    return 0;
}

/*
 * Get current search key.  For level 0 we don't actually have a key
 * structure so we make one up from the record.  For all other levels
 * we just return the right key.
 */
STATIC union xfs_btree_key *
xfs_lookup_get_search_key(
    struct xfs_btree_cur    *cur,
    int         level,
    int         keyno,
    struct xfs_btree_block  *block,
    union xfs_btree_key *kp)
{
    if (level == 0) {
        cur->bc_ops->init_key_from_rec(kp,
                xfs_btree_rec_addr(cur, keyno, block));
        return kp;
    }

    return xfs_btree_key_addr(cur, keyno, block);
}

/*
 * 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.
 */
int                 /* error */
xfs_btree_lookup(
    struct xfs_btree_cur    *cur,   /* btree cursor */
    xfs_lookup_t        dir,    /* <=, ==, or >= */
    int         *stat)  /* success/failure */
{
    struct xfs_btree_block  *block; /* current btree block */
    __int64_t       diff;   /* difference for the current key */
    int         error;  /* error return value */
    int         keyno;  /* current key number */
    int         level;  /* level in the btree */
    union xfs_btree_ptr *pp;    /* ptr to btree block */
    union xfs_btree_ptr ptr;    /* ptr to btree block */

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_TRACE_ARGI(cur, dir);

    XFS_BTREE_STATS_INC(cur, lookup);

    block = NULL;
    keyno = 0;

    /* initialise start pointer from cursor */
    cur->bc_ops->init_ptr_from_cur(cur, &ptr);
    pp = &ptr;

    /*
     * 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--) {
        /* Get the block we need to do the lookup on. */
        error = xfs_btree_lookup_get_block(cur, level, pp, &block);
        if (error)
            goto error0;

        if (diff == 0) {
            /*
             * If we already had a key match at a higher level, we
             * know we need to use the first entry in this block.
             */
            keyno = 1;
        } else {
            /* Otherwise search this block. Do a binary search. */

            int high;   /* high entry number */
            int low;    /* low entry number */

            /* Set low and high entry numbers, 1-based. */
            low = 1;
            high = xfs_btree_get_numrecs(block);
            if (!high) {
                /* Block is empty, must be an empty leaf. */
                ASSERT(level == 0 && cur->bc_nlevels == 1);

                cur->bc_ptrs[0] = dir != XFS_LOOKUP_LE;
                XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
                *stat = 0;
                return 0;
            }

            /* Binary search the block. */
            while (low <= high) {
                union xfs_btree_key key;
                union xfs_btree_key *kp;

                XFS_BTREE_STATS_INC(cur, compare);

                /* keyno is average of low and high. */
                keyno = (low + high) >> 1;

                /* Get current search key */
                kp = xfs_lookup_get_search_key(cur, level,
                        keyno, block, &key);

                /*
                 * Compute difference to get next direction:
                 *  - less than, move right
                 *  - greater than, move left
                 *  - equal, we're done
                 */
                diff = cur->bc_ops->key_diff(cur, kp);
                if (diff < 0)
                    low = keyno + 1;
                else if (diff > 0)
                    high = keyno - 1;
                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;
            pp = xfs_btree_ptr_addr(cur, keyno, block);

#ifdef DEBUG
            error = xfs_btree_check_ptr(cur, pp, 0, level);
            if (error)
                goto error0;
#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.
         */
        xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_RIGHTSIB);
        if (dir == XFS_LOOKUP_GE &&
            keyno > xfs_btree_get_numrecs(block) &&
            !xfs_btree_ptr_is_null(cur, &ptr)) {
            int i;

            cur->bc_ptrs[0] = keyno;
            error = xfs_btree_increment(cur, 0, &i);
            if (error)
                goto error0;
            XFS_WANT_CORRUPTED_RETURN(i == 1);
            XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
            *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 > xfs_btree_get_numrecs(block))
        *stat = 0;
    else if (dir != XFS_LOOKUP_EQ || diff == 0)
        *stat = 1;
    else
        *stat = 0;
    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    return 0;

error0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
    return error;
}

/*
 * Update keys at all levels from here to the root along the cursor's path.
 */
STATIC int
xfs_btree_updkey(
    struct xfs_btree_cur    *cur,
    union xfs_btree_key *keyp,
    int         level)
{
    struct xfs_btree_block  *block;
    struct xfs_buf      *bp;
    union xfs_btree_key *kp;
    int         ptr;

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_TRACE_ARGIK(cur, level, keyp);

    ASSERT(!(cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) || level >= 1);

    /*
     * 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++) {
#ifdef DEBUG
        int     error;
#endif
        block = xfs_btree_get_block(cur, level, &bp);
#ifdef DEBUG
        error = xfs_btree_check_block(cur, block, level, bp);
        if (error) {
            XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
            return error;
        }
#endif
        ptr = cur->bc_ptrs[level];
        kp = xfs_btree_key_addr(cur, ptr, block);
        xfs_btree_copy_keys(cur, kp, keyp, 1);
        xfs_btree_log_keys(cur, bp, ptr, ptr);
    }

    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    return 0;
}

/*
 * Update the record referred to by cur to the value in the
 * given record. This either works (return 0) or gets an
 * EFSCORRUPTED error.
 */
int
xfs_btree_update(
    struct xfs_btree_cur    *cur,
    union xfs_btree_rec *rec)
{
    struct xfs_btree_block  *block;
    struct xfs_buf      *bp;
    int         error;
    int         ptr;
    union xfs_btree_rec *rp;

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_TRACE_ARGR(cur, rec);

    /* Pick up the current block. */
    block = xfs_btree_get_block(cur, 0, &bp);

#ifdef DEBUG
    error = xfs_btree_check_block(cur, block, 0, bp);
    if (error)
        goto error0;
#endif
    /* Get the address of the rec to be updated. */
    ptr = cur->bc_ptrs[0];
    rp = xfs_btree_rec_addr(cur, ptr, block);

    /* Fill in the new contents and log them. */
    xfs_btree_copy_recs(cur, rp, rec, 1);
    xfs_btree_log_recs(cur, bp, ptr, ptr);

    /*
     * If we are tracking the last record in the tree and
     * we are at the far right edge of the tree, update it.
     */
    if (xfs_btree_is_lastrec(cur, block, 0)) {
        cur->bc_ops->update_lastrec(cur, block, rec,
                        ptr, LASTREC_UPDATE);
    }

    /* Updating first rec in leaf. Pass new key value up to our parent. */
    if (ptr == 1) {
        union xfs_btree_key key;

        cur->bc_ops->init_key_from_rec(&key, rec);
        error = xfs_btree_updkey(cur, &key, 1);
        if (error)
            goto error0;
    }

    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    return 0;

error0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
    return error;
}

/*
 * Move 1 record left from cur/level if possible.
 * Update cur to reflect the new path.
 */
STATIC int                  /* error */
xfs_btree_lshift(
    struct xfs_btree_cur    *cur,
    int         level,
    int         *stat)      /* success/failure */
{
    union xfs_btree_key key;        /* btree key */
    struct xfs_buf      *lbp;       /* left buffer pointer */
    struct xfs_btree_block  *left;      /* left btree block */
    int         lrecs;      /* left record count */
    struct xfs_buf      *rbp;       /* right buffer pointer */
    struct xfs_btree_block  *right;     /* right btree block */
    int         rrecs;      /* right record count */
    union xfs_btree_ptr lptr;       /* left btree pointer */
    union xfs_btree_key *rkp = NULL;    /* right btree key */
    union xfs_btree_ptr *rpp = NULL;    /* right address pointer */
    union xfs_btree_rec *rrp = NULL;    /* right record pointer */
    int         error;      /* error return value */

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_TRACE_ARGI(cur, level);

    if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
        level == cur->bc_nlevels - 1)
        goto out0;

    /* Set up variables for this block as "right". */
    right = xfs_btree_get_block(cur, level, &rbp);

#ifdef DEBUG
    error = xfs_btree_check_block(cur, right, level, rbp);
    if (error)
        goto error0;
#endif

    /* If we've got no left sibling then we can't shift an entry left. */
    xfs_btree_get_sibling(cur, right, &lptr, XFS_BB_LEFTSIB);
    if (xfs_btree_ptr_is_null(cur, &lptr))
        goto out0;

    /*
     * 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)
        goto out0;

    /* Set up the left neighbor as "left". */
    error = xfs_btree_read_buf_block(cur, &lptr, level, 0, &left, &lbp);
    if (error)
        goto error0;

    /* If it's full, it can't take another entry. */
    lrecs = xfs_btree_get_numrecs(left);
    if (lrecs == cur->bc_ops->get_maxrecs(cur, level))
        goto out0;

    rrecs = xfs_btree_get_numrecs(right);

    /*
     * We add one entry to the left side and remove one for the right side.
     * Account for it here, the changes will be updated on disk and logged
     * later.
     */
    lrecs++;
    rrecs--;

    XFS_BTREE_STATS_INC(cur, lshift);
    XFS_BTREE_STATS_ADD(cur, moves, 1);

    /*
     * If non-leaf, copy a key and a ptr to the left block.
     * Log the changes to the left block.
     */
    if (level > 0) {
        /* It's a non-leaf.  Move keys and pointers. */
        union xfs_btree_key *lkp;   /* left btree key */
        union xfs_btree_ptr *lpp;   /* left address pointer */

        lkp = xfs_btree_key_addr(cur, lrecs, left);
        rkp = xfs_btree_key_addr(cur, 1, right);

        lpp = xfs_btree_ptr_addr(cur, lrecs, left);
        rpp = xfs_btree_ptr_addr(cur, 1, right);
#ifdef DEBUG
        error = xfs_btree_check_ptr(cur, rpp, 0, level);
        if (error)
            goto error0;
#endif
        xfs_btree_copy_keys(cur, lkp, rkp, 1);
        xfs_btree_copy_ptrs(cur, lpp, rpp, 1);

        xfs_btree_log_keys(cur, lbp, lrecs, lrecs);
        xfs_btree_log_ptrs(cur, lbp, lrecs, lrecs);

        ASSERT(cur->bc_ops->keys_inorder(cur,
            xfs_btree_key_addr(cur, lrecs - 1, left), lkp));
    } else {
        /* It's a leaf.  Move records.  */
        union xfs_btree_rec *lrp;   /* left record pointer */

        lrp = xfs_btree_rec_addr(cur, lrecs, left);
        rrp = xfs_btree_rec_addr(cur, 1, right);

        xfs_btree_copy_recs(cur, lrp, rrp, 1);
        xfs_btree_log_recs(cur, lbp, lrecs, lrecs);

        ASSERT(cur->bc_ops->recs_inorder(cur,
            xfs_btree_rec_addr(cur, lrecs - 1, left), lrp));
    }

    xfs_btree_set_numrecs(left, lrecs);
    xfs_btree_log_block(cur, lbp, XFS_BB_NUMRECS);

    xfs_btree_set_numrecs(right, rrecs);
    xfs_btree_log_block(cur, rbp, XFS_BB_NUMRECS);

    /*
     * Slide the contents of right down one entry.
     */
    XFS_BTREE_STATS_ADD(cur, moves, rrecs - 1);
    if (level > 0) {
        /* It's a nonleaf. operate on keys and ptrs */
#ifdef DEBUG
        int         i;      /* loop index */

        for (i = 0; i < rrecs; i++) {
            error = xfs_btree_check_ptr(cur, rpp, i + 1, level);
            if (error)
                goto error0;
        }
#endif
        xfs_btree_shift_keys(cur,
                xfs_btree_key_addr(cur, 2, right),
                -1, rrecs);
        xfs_btree_shift_ptrs(cur,
                xfs_btree_ptr_addr(cur, 2, right),
                -1, rrecs);

        xfs_btree_log_keys(cur, rbp, 1, rrecs);
        xfs_btree_log_ptrs(cur, rbp, 1, rrecs);
    } else {
        /* It's a leaf. operate on records */
        xfs_btree_shift_recs(cur,
            xfs_btree_rec_addr(cur, 2, right),
            -1, rrecs);
        xfs_btree_log_recs(cur, rbp, 1, rrecs);

        /*
         * If it's the first record in the block, we'll need a key
         * structure to pass up to the next level (updkey).
         */
        cur->bc_ops->init_key_from_rec(&key,
            xfs_btree_rec_addr(cur, 1, right));
        rkp = &key;
    }

    /* Update the parent key values of right. */
    error = xfs_btree_updkey(cur, rkp, level + 1);
    if (error)
        goto error0;

    /* Slide the cursor value left one. */
    cur->bc_ptrs[level]--;

    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = 1;
    return 0;

out0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = 0;
    return 0;

error0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
    return error;
}

/*
 * Move 1 record right from cur/level if possible.
 * Update cur to reflect the new path.
 */
STATIC int                  /* error */
xfs_btree_rshift(
    struct xfs_btree_cur    *cur,
    int         level,
    int         *stat)      /* success/failure */
{
    union xfs_btree_key key;        /* btree key */
    struct xfs_buf      *lbp;       /* left buffer pointer */
    struct xfs_btree_block  *left;      /* left btree block */
    struct xfs_buf      *rbp;       /* right buffer pointer */
    struct xfs_btree_block  *right;     /* right btree block */
    struct xfs_btree_cur    *tcur;      /* temporary btree cursor */
    union xfs_btree_ptr rptr;       /* right block pointer */
    union xfs_btree_key *rkp;       /* right btree key */
    int         rrecs;      /* right record count */
    int         lrecs;      /* left record count */
    int         error;      /* error return value */
    int         i;      /* loop counter */

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_TRACE_ARGI(cur, level);

    if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
        (level == cur->bc_nlevels - 1))
        goto out0;

    /* Set up variables for this block as "left". */
    left = xfs_btree_get_block(cur, level, &lbp);

#ifdef DEBUG
    error = xfs_btree_check_block(cur, left, level, lbp);
    if (error)
        goto error0;
#endif

    /* If we've got no right sibling then we can't shift an entry right. */
    xfs_btree_get_sibling(cur, left, &rptr, XFS_BB_RIGHTSIB);
    if (xfs_btree_ptr_is_null(cur, &rptr))
        goto out0;

    /*
     * If the cursor entry is the one that would be moved, don't
     * do it... it's too complicated.
     */
    lrecs = xfs_btree_get_numrecs(left);
    if (cur->bc_ptrs[level] >= lrecs)
        goto out0;

    /* Set up the right neighbor as "right". */
    error = xfs_btree_read_buf_block(cur, &rptr, level, 0, &right, &rbp);
    if (error)
        goto error0;

    /* If it's full, it can't take another entry. */
    rrecs = xfs_btree_get_numrecs(right);
    if (rrecs == cur->bc_ops->get_maxrecs(cur, level))
        goto out0;

    XFS_BTREE_STATS_INC(cur, rshift);
    XFS_BTREE_STATS_ADD(cur, moves, rrecs);

    /*
     * Make a hole at the start of the right neighbor block, then
     * copy the last left block entry to the hole.
     */
    if (level > 0) {
        /* It's a nonleaf. make a hole in the keys and ptrs */
        union xfs_btree_key *lkp;
        union xfs_btree_ptr *lpp;
        union xfs_btree_ptr *rpp;

        lkp = xfs_btree_key_addr(cur, lrecs, left);
        lpp = xfs_btree_ptr_addr(cur, lrecs, left);
        rkp = xfs_btree_key_addr(cur, 1, right);
        rpp = xfs_btree_ptr_addr(cur, 1, right);

#ifdef DEBUG
        for (i = rrecs - 1; i >= 0; i--) {
            error = xfs_btree_check_ptr(cur, rpp, i, level);
            if (error)
                goto error0;
        }
#endif

        xfs_btree_shift_keys(cur, rkp, 1, rrecs);
        xfs_btree_shift_ptrs(cur, rpp, 1, rrecs);

#ifdef DEBUG
        error = xfs_btree_check_ptr(cur, lpp, 0, level);
        if (error)
            goto error0;
#endif

        /* Now put the new data in, and log it. */
        xfs_btree_copy_keys(cur, rkp, lkp, 1);
        xfs_btree_copy_ptrs(cur, rpp, lpp, 1);

        xfs_btree_log_keys(cur, rbp, 1, rrecs + 1);
        xfs_btree_log_ptrs(cur, rbp, 1, rrecs + 1);

        ASSERT(cur->bc_ops->keys_inorder(cur, rkp,
            xfs_btree_key_addr(cur, 2, right)));
    } else {
        /* It's a leaf. make a hole in the records */
        union xfs_btree_rec *lrp;
        union xfs_btree_rec *rrp;

        lrp = xfs_btree_rec_addr(cur, lrecs, left);
        rrp = xfs_btree_rec_addr(cur, 1, right);

        xfs_btree_shift_recs(cur, rrp, 1, rrecs);

        /* Now put the new data in, and log it. */
        xfs_btree_copy_recs(cur, rrp, lrp, 1);
        xfs_btree_log_recs(cur, rbp, 1, rrecs + 1);

        cur->bc_ops->init_key_from_rec(&key, rrp);
        rkp = &key;

        ASSERT(cur->bc_ops->recs_inorder(cur, rrp,
            xfs_btree_rec_addr(cur, 2, right)));
    }

    /*
     * Decrement and log left's numrecs, bump and log right's numrecs.
     */
    xfs_btree_set_numrecs(left, --lrecs);
    xfs_btree_log_block(cur, lbp, XFS_BB_NUMRECS);

    xfs_btree_set_numrecs(right, ++rrecs);
    xfs_btree_log_block(cur, rbp, XFS_BB_NUMRECS);

    /*
     * Using a temporary cursor, update the parent key values of the
     * block on the right.
     */
    error = xfs_btree_dup_cursor(cur, &tcur);
    if (error)
        goto error0;
    i = xfs_btree_lastrec(tcur, level);
    XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

    error = xfs_btree_increment(tcur, level, &i);
    if (error)
        goto error1;

    error = xfs_btree_updkey(tcur, rkp, level + 1);
    if (error)
        goto error1;

    xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);

    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = 1;
    return 0;

out0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = 0;
    return 0;

error0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
    return error;

error1:
    XFS_BTREE_TRACE_CURSOR(tcur, XBT_ERROR);
    xfs_btree_del_cursor(tcur, XFS_BTREE_ERROR);
    return error;
}

/*
 * Split cur/level block in half.
 * Return new block number and the key to its first
 * record (to be inserted into parent).
 */
STATIC int                  /* error */
xfs_btree_split(
    struct xfs_btree_cur    *cur,
    int         level,
    union xfs_btree_ptr *ptrp,
    union xfs_btree_key *key,
    struct xfs_btree_cur    **curp,
    int         *stat)      /* success/failure */
{
    union xfs_btree_ptr lptr;       /* left sibling block ptr */
    struct xfs_buf      *lbp;       /* left buffer pointer */
    struct xfs_btree_block  *left;      /* left btree block */
    union xfs_btree_ptr rptr;       /* right sibling block ptr */
    struct xfs_buf      *rbp;       /* right buffer pointer */
    struct xfs_btree_block  *right;     /* right btree block */
    union xfs_btree_ptr rrptr;      /* right-right sibling ptr */
    struct xfs_buf      *rrbp;      /* right-right buffer pointer */
    struct xfs_btree_block  *rrblock;   /* right-right btree block */
    int         lrecs;
    int         rrecs;
    int         src_index;
    int         error;      /* error return value */
#ifdef DEBUG
    int         i;
#endif

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_TRACE_ARGIPK(cur, level, *ptrp, key);

    XFS_BTREE_STATS_INC(cur, split);

    /* Set up left block (current one). */
    left = xfs_btree_get_block(cur, level, &lbp);

#ifdef DEBUG
    error = xfs_btree_check_block(cur, left, level, lbp);
    if (error)
        goto error0;
#endif

    xfs_btree_buf_to_ptr(cur, lbp, &lptr);

    /* Allocate the new block. If we can't do it, we're toast. Give up. */
    error = cur->bc_ops->alloc_block(cur, &lptr, &rptr, 1, stat);
    if (error)
        goto error0;
    if (*stat == 0)
        goto out0;
    XFS_BTREE_STATS_INC(cur, alloc);

    /* Set up the new block as "right". */
    error = xfs_btree_get_buf_block(cur, &rptr, 0, &right, &rbp);
    if (error)
        goto error0;

    /* Fill in the btree header for the new right block. */
    xfs_btree_init_block(cur, xfs_btree_get_level(left), 0, right);

    /*
     * Split the entries between the old and the new block evenly.
     * Make sure that if there's an odd number of entries now, that
     * each new block will have the same number of entries.
     */
    lrecs = xfs_btree_get_numrecs(left);
    rrecs = lrecs / 2;
    if ((lrecs & 1) && cur->bc_ptrs[level] <= rrecs + 1)
        rrecs++;
    src_index = (lrecs - rrecs + 1);

    XFS_BTREE_STATS_ADD(cur, moves, rrecs);

    /*
     * Copy btree block entries from the left block over to the
     * new block, the right. Update the right block and log the
     * changes.
     */
    if (level > 0) {
        /* It's a non-leaf.  Move keys and pointers. */
        union xfs_btree_key *lkp;   /* left btree key */
        union xfs_btree_ptr *lpp;   /* left address pointer */
        union xfs_btree_key *rkp;   /* right btree key */
        union xfs_btree_ptr *rpp;   /* right address pointer */

        lkp = xfs_btree_key_addr(cur, src_index, left);
        lpp = xfs_btree_ptr_addr(cur, src_index, left);
        rkp = xfs_btree_key_addr(cur, 1, right);
        rpp = xfs_btree_ptr_addr(cur, 1, right);

#ifdef DEBUG
        for (i = src_index; i < rrecs; i++) {
            error = xfs_btree_check_ptr(cur, lpp, i, level);
            if (error)
                goto error0;
        }
#endif

        xfs_btree_copy_keys(cur, rkp, lkp, rrecs);
        xfs_btree_copy_ptrs(cur, rpp, lpp, rrecs);

        xfs_btree_log_keys(cur, rbp, 1, rrecs);
        xfs_btree_log_ptrs(cur, rbp, 1, rrecs);

        /* Grab the keys to the entries moved to the right block */
        xfs_btree_copy_keys(cur, key, rkp, 1);
    } else {
        /* It's a leaf.  Move records.  */
        union xfs_btree_rec *lrp;   /* left record pointer */
        union xfs_btree_rec *rrp;   /* right record pointer */

        lrp = xfs_btree_rec_addr(cur, src_index, left);
        rrp = xfs_btree_rec_addr(cur, 1, right);

        xfs_btree_copy_recs(cur, rrp, lrp, rrecs);
        xfs_btree_log_recs(cur, rbp, 1, rrecs);

        cur->bc_ops->init_key_from_rec(key,
            xfs_btree_rec_addr(cur, 1, right));
    }


    /*
     * Find the left block number by looking in the buffer.
     * Adjust numrecs, sibling pointers.
     */
    xfs_btree_get_sibling(cur, left, &rrptr, XFS_BB_RIGHTSIB);
    xfs_btree_set_sibling(cur, right, &rrptr, XFS_BB_RIGHTSIB);
    xfs_btree_set_sibling(cur, right, &lptr, XFS_BB_LEFTSIB);
    xfs_btree_set_sibling(cur, left, &rptr, XFS_BB_RIGHTSIB);

    lrecs -= rrecs;
    xfs_btree_set_numrecs(left, lrecs);
    xfs_btree_set_numrecs(right, xfs_btree_get_numrecs(right) + rrecs);

    xfs_btree_log_block(cur, rbp, XFS_BB_ALL_BITS);
    xfs_btree_log_block(cur, 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 (!xfs_btree_ptr_is_null(cur, &rrptr)) {
        error = xfs_btree_read_buf_block(cur, &rrptr, level,
                            0, &rrblock, &rrbp);
        if (error)
            goto error0;
        xfs_btree_set_sibling(cur, rrblock, &rptr, XFS_BB_LEFTSIB);
        xfs_btree_log_block(cur, 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] > lrecs + 1) {
        xfs_btree_setbuf(cur, level, rbp);
        cur->bc_ptrs[level] -= lrecs;
    }
    /*
     * 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) {
        error = xfs_btree_dup_cursor(cur, curp);
        if (error)
            goto error0;
        (*curp)->bc_ptrs[level + 1]++;
    }
    *ptrp = rptr;
    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = 1;
    return 0;
out0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = 0;
    return 0;

error0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
    return error;
}

/*
 * Copy the old inode root contents into a real block and make the
 * broot point to it.
 */
int                     /* error */
xfs_btree_new_iroot(
    struct xfs_btree_cur    *cur,       /* btree cursor */
    int         *logflags,  /* logging flags for inode */
    int         *stat)      /* return status - 0 fail */
{
    struct xfs_buf      *cbp;       /* buffer for cblock */
    struct xfs_btree_block  *block;     /* btree block */
    struct xfs_btree_block  *cblock;    /* child btree block */
    union xfs_btree_key *ckp;       /* child key pointer */
    union xfs_btree_ptr *cpp;       /* child ptr pointer */
    union xfs_btree_key *kp;        /* pointer to btree key */
    union xfs_btree_ptr *pp;        /* pointer to block addr */
    union xfs_btree_ptr nptr;       /* new block addr */
    int         level;      /* btree level */
    int         error;      /* error return code */
#ifdef DEBUG
    int         i;      /* loop counter */
#endif

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_STATS_INC(cur, newroot);

    ASSERT(cur->bc_flags & XFS_BTREE_ROOT_IN_INODE);

    level = cur->bc_nlevels - 1;

    block = xfs_btree_get_iroot(cur);
    pp = xfs_btree_ptr_addr(cur, 1, block);

    /* Allocate the new block. If we can't do it, we're toast. Give up. */
    error = cur->bc_ops->alloc_block(cur, pp, &nptr, 1, stat);
    if (error)
        goto error0;
    if (*stat == 0) {
        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
        return 0;
    }
    XFS_BTREE_STATS_INC(cur, alloc);

    /* Copy the root into a real block. */
    error = xfs_btree_get_buf_block(cur, &nptr, 0, &cblock, &cbp);
    if (error)
        goto error0;

    memcpy(cblock, block, xfs_btree_block_len(cur));

    be16_add_cpu(&block->bb_level, 1);
    xfs_btree_set_numrecs(block, 1);
    cur->bc_nlevels++;
    cur->bc_ptrs[level + 1] = 1;

    kp = xfs_btree_key_addr(cur, 1, block);
    ckp = xfs_btree_key_addr(cur, 1, cblock);
    xfs_btree_copy_keys(cur, ckp, kp, xfs_btree_get_numrecs(cblock));

    cpp = xfs_btree_ptr_addr(cur, 1, cblock);
#ifdef DEBUG
    for (i = 0; i < be16_to_cpu(cblock->bb_numrecs); i++) {
        error = xfs_btree_check_ptr(cur, pp, i, level);
        if (error)
            goto error0;
    }
#endif
    xfs_btree_copy_ptrs(cur, cpp, pp, xfs_btree_get_numrecs(cblock));

#ifdef DEBUG
    error = xfs_btree_check_ptr(cur, &nptr, 0, level);
    if (error)
        goto error0;
#endif
    xfs_btree_copy_ptrs(cur, pp, &nptr, 1);

    xfs_iroot_realloc(cur->bc_private.b.ip,
              1 - xfs_btree_get_numrecs(cblock),
              cur->bc_private.b.whichfork);

    xfs_btree_setbuf(cur, level, cbp);

    /*
     * Do all this logging at the end so that
     * the root is at the right level.
     */
    xfs_btree_log_block(cur, cbp, XFS_BB_ALL_BITS);
    xfs_btree_log_keys(cur, cbp, 1, be16_to_cpu(cblock->bb_numrecs));
    xfs_btree_log_ptrs(cur, cbp, 1, be16_to_cpu(cblock->bb_numrecs));

    *logflags |=
        XFS_ILOG_CORE | xfs_ilog_fbroot(cur->bc_private.b.whichfork);
    *stat = 1;
    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    return 0;
error0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
    return error;
}

/*
 * Allocate a new root block, fill it in.
 */
STATIC int              /* error */
xfs_btree_new_root(
    struct xfs_btree_cur    *cur,   /* btree cursor */
    int         *stat)  /* success/failure */
{
    struct xfs_btree_block  *block; /* one half of the old root block */
    struct xfs_buf      *bp;    /* buffer containing block */
    int         error;  /* error return value */
    struct xfs_buf      *lbp;   /* left buffer pointer */
    struct xfs_btree_block  *left;  /* left btree block */
    struct xfs_buf      *nbp;   /* new (root) buffer */
    struct xfs_btree_block  *new;   /* new (root) btree block */
    int         nptr;   /* new value for key index, 1 or 2 */
    struct xfs_buf      *rbp;   /* right buffer pointer */
    struct xfs_btree_block  *right; /* right btree block */
    union xfs_btree_ptr rptr;
    union xfs_btree_ptr lptr;

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_STATS_INC(cur, newroot);

    /* initialise our start point from the cursor */
    cur->bc_ops->init_ptr_from_cur(cur, &rptr);

    /* Allocate the new block. If we can't do it, we're toast. Give up. */
    error = cur->bc_ops->alloc_block(cur, &rptr, &lptr, 1, stat);
    if (error)
        goto error0;
    if (*stat == 0)
        goto out0;
    XFS_BTREE_STATS_INC(cur, alloc);

    /* Set up the new block. */
    error = xfs_btree_get_buf_block(cur, &lptr, 0, &new, &nbp);
    if (error)
        goto error0;

    /* Set the root in the holding structure  increasing the level by 1. */
    cur->bc_ops->set_root(cur, &lptr, 1);

    /*
     * 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.
     */
    block = xfs_btree_get_block(cur, cur->bc_nlevels - 1, &bp);

#ifdef DEBUG
    error = xfs_btree_check_block(cur, block, cur->bc_nlevels - 1, bp);
    if (error)
        goto error0;
#endif

    xfs_btree_get_sibling(cur, block, &rptr, XFS_BB_RIGHTSIB);
    if (!xfs_btree_ptr_is_null(cur, &rptr)) {
        /* Our block is left, pick up the right block. */
        lbp = bp;
        xfs_btree_buf_to_ptr(cur, lbp, &lptr);
        left = block;
        error = xfs_btree_read_buf_block(cur, &rptr,
                    cur->bc_nlevels - 1, 0, &right, &rbp);
        if (error)
            goto error0;
        bp = rbp;
        nptr = 1;
    } else {
        /* Our block is right, pick up the left block. */
        rbp = bp;
        xfs_btree_buf_to_ptr(cur, rbp, &rptr);
        right = block;
        xfs_btree_get_sibling(cur, right, &lptr, XFS_BB_LEFTSIB);
        error = xfs_btree_read_buf_block(cur, &lptr,
                    cur->bc_nlevels - 1, 0, &left, &lbp);
        if (error)
            goto error0;
        bp = lbp;
        nptr = 2;
    }
    /* Fill in the new block's btree header and log it. */
    xfs_btree_init_block(cur, cur->bc_nlevels, 2, new);
    xfs_btree_log_block(cur, nbp, XFS_BB_ALL_BITS);
    ASSERT(!xfs_btree_ptr_is_null(cur, &lptr) &&
            !xfs_btree_ptr_is_null(cur, &rptr));

    /* Fill in the key data in the new root. */
    if (xfs_btree_get_level(left) > 0) {
        xfs_btree_copy_keys(cur,
                xfs_btree_key_addr(cur, 1, new),
                xfs_btree_key_addr(cur, 1, left), 1);
        xfs_btree_copy_keys(cur,
                xfs_btree_key_addr(cur, 2, new),
                xfs_btree_key_addr(cur, 1, right), 1);
    } else {
        cur->bc_ops->init_key_from_rec(
                xfs_btree_key_addr(cur, 1, new),
                xfs_btree_rec_addr(cur, 1, left));
        cur->bc_ops->init_key_from_rec(
                xfs_btree_key_addr(cur, 2, new),
                xfs_btree_rec_addr(cur, 1, right));
    }
    xfs_btree_log_keys(cur, nbp, 1, 2);

    /* Fill in the pointer data in the new root. */
    xfs_btree_copy_ptrs(cur,
        xfs_btree_ptr_addr(cur, 1, new), &lptr, 1);
    xfs_btree_copy_ptrs(cur,
        xfs_btree_ptr_addr(cur, 2, new), &rptr, 1);
    xfs_btree_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++;
    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = 1;
    return 0;
error0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
    return error;
out0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = 0;
    return 0;
}

STATIC int
xfs_btree_make_block_unfull(
    struct xfs_btree_cur    *cur,   /* btree cursor */
    int         level,  /* btree level */
    int         numrecs,/* # of recs in block */
    int         *oindex,/* old tree index */
    int         *index, /* new tree index */
    union xfs_btree_ptr *nptr,  /* new btree ptr */
    struct xfs_btree_cur    **ncur, /* new btree cursor */
    union xfs_btree_rec *nrec,  /* new record */
    int         *stat)
{
    union xfs_btree_key key;    /* new btree key value */
    int         error = 0;

    if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
        level == cur->bc_nlevels - 1) {
            struct xfs_inode *ip = cur->bc_private.b.ip;

        if (numrecs < cur->bc_ops->get_dmaxrecs(cur, level)) {
            /* A root block that can be made bigger. */

            xfs_iroot_realloc(ip, 1, cur->bc_private.b.whichfork);
        } else {
            /* A root block that needs replacing */
            int logflags = 0;

            error = xfs_btree_new_iroot(cur, &logflags, stat);
            if (error || *stat == 0)
                return error;

            xfs_trans_log_inode(cur->bc_tp, ip, logflags);
        }

        return 0;
    }

    /* First, try shifting an entry to the right neighbor. */
    error = xfs_btree_rshift(cur, level, stat);
    if (error || *stat)
        return error;

    /* Next, try shifting an entry to the left neighbor. */
    error = xfs_btree_lshift(cur, level, stat);
    if (error)
        return error;

    if (*stat) {
        *oindex = *index = cur->bc_ptrs[level];
        return 0;
    }

    /*
     * 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.
     */
    error = xfs_btree_split(cur, level, nptr, &key, ncur, stat);
    if (error || *stat == 0)
        return error;


    *index = cur->bc_ptrs[level];
    cur->bc_ops->init_rec_from_key(&key, nrec);
    return 0;
}

/*
 * Insert one record/level.  Return information to the caller
 * allowing the next level up to proceed if necessary.
 */
STATIC int
xfs_btree_insrec(
    struct xfs_btree_cur    *cur,   /* btree cursor */
    int         level,  /* level to insert record at */
    union xfs_btree_ptr *ptrp,  /* i/o: block number inserted */
    union xfs_btree_rec *recp,  /* i/o: record data inserted */
    struct xfs_btree_cur    **curp, /* output: new cursor replacing cur */
    int         *stat)  /* success/failure */
{
    struct xfs_btree_block  *block; /* btree block */
    struct xfs_buf      *bp;    /* buffer for block */
    union xfs_btree_key key;    /* btree key */
    union xfs_btree_ptr nptr;   /* new block ptr */
    struct xfs_btree_cur    *ncur;  /* new btree cursor */
    union xfs_btree_rec nrec;   /* new record count */
    int         optr;   /* old key/record index */
    int         ptr;    /* key/record index */
    int         numrecs;/* number of records */
    int         error;  /* error return value */
#ifdef DEBUG
    int         i;
#endif

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_TRACE_ARGIPR(cur, level, *ptrp, recp);

    ncur = NULL;

    /*
     * If we have an external root pointer, and we've made it to the
     * root level, allocate a new root block and we're done.
     */
    if (!(cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) &&
        (level >= cur->bc_nlevels)) {
        error = xfs_btree_new_root(cur, stat);
        xfs_btree_set_ptr_null(cur, ptrp);

        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
        return error;
    }

    /* If we're off the left edge, return failure. */
    ptr = cur->bc_ptrs[level];
    if (ptr == 0) {
        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
        *stat = 0;
        return 0;
    }

    /* Make a key out of the record data to be inserted, and save it. */
    cur->bc_ops->init_key_from_rec(&key, recp);

    optr = ptr;

    XFS_BTREE_STATS_INC(cur, insrec);

    /* Get pointers to the btree buffer and block. */
    block = xfs_btree_get_block(cur, level, &bp);
    numrecs = xfs_btree_get_numrecs(block);

#ifdef DEBUG
    error = xfs_btree_check_block(cur, block, level, bp);
    if (error)
        goto error0;

    /* Check that the new entry is being inserted in the right place. */
    if (ptr <= numrecs) {
        if (level == 0) {
            ASSERT(cur->bc_ops->recs_inorder(cur, recp,
                xfs_btree_rec_addr(cur, ptr, block)));
        } else {
            ASSERT(cur->bc_ops->keys_inorder(cur, &key,
                xfs_btree_key_addr(cur, ptr, block)));
        }
    }
#endif

    /*
     * If the block is full, we can't insert the new entry until we
     * make the block un-full.
     */
    xfs_btree_set_ptr_null(cur, &nptr);
    if (numrecs == cur->bc_ops->get_maxrecs(cur, level)) {
        error = xfs_btree_make_block_unfull(cur, level, numrecs,
                    &optr, &ptr, &nptr, &ncur, &nrec, stat);
        if (error || *stat == 0)
            goto error0;
    }

    /*
     * The current block may have changed if the block was
     * previously full and we have just made space in it.
     */
    block = xfs_btree_get_block(cur, level, &bp);
    numrecs = xfs_btree_get_numrecs(block);

#ifdef DEBUG
    error = xfs_btree_check_block(cur, block, level, bp);
    if (error)
        return error;
#endif

    /*
     * At this point we know there's room for our new entry in the block
     * we're pointing at.
     */
    XFS_BTREE_STATS_ADD(cur, moves, numrecs - ptr + 1);

    if (level > 0) {
        /* It's a nonleaf. make a hole in the keys and ptrs */
        union xfs_btree_key *kp;
        union xfs_btree_ptr *pp;

        kp = xfs_btree_key_addr(cur, ptr, block);
        pp = xfs_btree_ptr_addr(cur, ptr, block);

#ifdef DEBUG
        for (i = numrecs - ptr; i >= 0; i--) {
            error = xfs_btree_check_ptr(cur, pp, i, level);
            if (error)
                return error;
        }
#endif

        xfs_btree_shift_keys(cur, kp, 1, numrecs - ptr + 1);
        xfs_btree_shift_ptrs(cur, pp, 1, numrecs - ptr + 1);

#ifdef DEBUG
        error = xfs_btree_check_ptr(cur, ptrp, 0, level);
        if (error)
            goto error0;
#endif

        /* Now put the new data in, bump numrecs and log it. */
        xfs_btree_copy_keys(cur, kp, &key, 1);
        xfs_btree_copy_ptrs(cur, pp, ptrp, 1);
        numrecs++;
        xfs_btree_set_numrecs(block, numrecs);
        xfs_btree_log_ptrs(cur, bp, ptr, numrecs);
        xfs_btree_log_keys(cur, bp, ptr, numrecs);
#ifdef DEBUG
        if (ptr < numrecs) {
            ASSERT(cur->bc_ops->keys_inorder(cur, kp,
                xfs_btree_key_addr(cur, ptr + 1, block)));
        }
#endif
    } else {
        /* It's a leaf. make a hole in the records */
        union xfs_btree_rec             *rp;

        rp = xfs_btree_rec_addr(cur, ptr, block);

        xfs_btree_shift_recs(cur, rp, 1, numrecs - ptr + 1);

        /* Now put the new data in, bump numrecs and log it. */
        xfs_btree_copy_recs(cur, rp, recp, 1);
        xfs_btree_set_numrecs(block, ++numrecs);
        xfs_btree_log_recs(cur, bp, ptr, numrecs);
#ifdef DEBUG
        if (ptr < numrecs) {
            ASSERT(cur->bc_ops->recs_inorder(cur, rp,
                xfs_btree_rec_addr(cur, ptr + 1, block)));
        }
#endif
    }

    /* Log the new number of records in the btree header. */
    xfs_btree_log_block(cur, bp, XFS_BB_NUMRECS);

    /* If we inserted at the start of a block, update the parents' keys. */
    if (optr == 1) {
        error = xfs_btree_updkey(cur, &key, level + 1);
        if (error)
            goto error0;
    }

    /*
     * If we are tracking the last record in the tree and
     * we are at the far right edge of the tree, update it.
     */
    if (xfs_btree_is_lastrec(cur, block, level)) {
        cur->bc_ops->update_lastrec(cur, block, recp,
                        ptr, LASTREC_INSREC);
    }

    /*
     * Return the new block number, if any.
     * If there is one, give back a record value and a cursor too.
     */
    *ptrp = nptr;
    if (!xfs_btree_ptr_is_null(cur, &nptr)) {
        *recp = nrec;
        *curp = ncur;
    }

    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = 1;
    return 0;

error0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
    return error;
}

/*
 * Insert the record at the point referenced by cur.
 *
 * A multi-level split of the tree on insert will invalidate the original
 * cursor.  All callers of this function should assume that the cursor is
 * no longer valid and revalidate it.
 */
int
xfs_btree_insert(
    struct xfs_btree_cur    *cur,
    int         *stat)
{
    int         error;  /* error return value */
    int         i;  /* result value, 0 for failure */
    int         level;  /* current level number in btree */
    union xfs_btree_ptr nptr;   /* new block number (split result) */
    struct xfs_btree_cur    *ncur;  /* new cursor (split result) */
    struct xfs_btree_cur    *pcur;  /* previous level's cursor */
    union xfs_btree_rec rec;    /* record to insert */

    level = 0;
    ncur = NULL;
    pcur = cur;

    xfs_btree_set_ptr_null(cur, &nptr);
    cur->bc_ops->init_rec_from_cur(cur, &rec);

    /*
     * 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/nptr into this level of the tree.
         * Note if we fail, nptr will be null.
         */
        error = xfs_btree_insrec(pcur, level, &nptr, &rec, &ncur, &i);
        if (error) {
            if (pcur != cur)
                xfs_btree_del_cursor(pcur, XFS_BTREE_ERROR);
            goto error0;
        }

        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
        level++;

        /*
         * 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 || xfs_btree_ptr_is_null(cur, &nptr))) {
            /* Save the state from the cursor before we trash it */
            if (cur->bc_ops->update_cursor)
                cur->bc_ops->update_cursor(pcur, cur);
            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 = NULL;
        }
    } while (!xfs_btree_ptr_is_null(cur, &nptr));

    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = i;
    return 0;
error0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
    return error;
}

/*
 * Try to merge a non-leaf block back into the inode root.
 *
 * Note: the killroot names comes from the fact that we're effectively
 * killing the old root block.  But because we can't just delete the
 * inode we have to copy the single block it was pointing to into the
 * inode.
 */
STATIC int
xfs_btree_kill_iroot(
    struct xfs_btree_cur    *cur)
{
    int         whichfork = cur->bc_private.b.whichfork;
    struct xfs_inode    *ip = cur->bc_private.b.ip;
    struct xfs_ifork    *ifp = XFS_IFORK_PTR(ip, whichfork);
    struct xfs_btree_block  *block;
    struct xfs_btree_block  *cblock;
    union xfs_btree_key *kp;
    union xfs_btree_key *ckp;
    union xfs_btree_ptr *pp;
    union xfs_btree_ptr *cpp;
    struct xfs_buf      *cbp;
    int         level;
    int         index;
    int         numrecs;
#ifdef DEBUG
    union xfs_btree_ptr ptr;
    int         i;
#endif

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);

    ASSERT(cur->bc_flags & XFS_BTREE_ROOT_IN_INODE);
    ASSERT(cur->bc_nlevels > 1);

    /*
     * Don't deal with the root block needs to be a leaf case.
     * We're just going to turn the thing back into extents anyway.
     */
    level = cur->bc_nlevels - 1;
    if (level == 1)
        goto out0;

    /*
     * Give up if the root has multiple children.
     */
    block = xfs_btree_get_iroot(cur);
    if (xfs_btree_get_numrecs(block) != 1)
        goto out0;

    cblock = xfs_btree_get_block(cur, level - 1, &cbp);
    numrecs = xfs_btree_get_numrecs(cblock);

    /*
     * Only do this if the next level will fit.
     * Then the data must be copied up to the inode,
     * instead of freeing the root you free the next level.
     */
    if (numrecs > cur->bc_ops->get_dmaxrecs(cur, level))
        goto out0;

    XFS_BTREE_STATS_INC(cur, killroot);

#ifdef DEBUG
    xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_LEFTSIB);
    ASSERT(xfs_btree_ptr_is_null(cur, &ptr));
    xfs_btree_get_sibling(cur, block, &ptr, XFS_BB_RIGHTSIB);
    ASSERT(xfs_btree_ptr_is_null(cur, &ptr));
#endif

    index = numrecs - cur->bc_ops->get_maxrecs(cur, level);
    if (index) {
        xfs_iroot_realloc(cur->bc_private.b.ip, index,
                  cur->bc_private.b.whichfork);
        block = ifp->if_broot;
    }

    be16_add_cpu(&block->bb_numrecs, index);
    ASSERT(block->bb_numrecs == cblock->bb_numrecs);

    kp = xfs_btree_key_addr(cur, 1, block);
    ckp = xfs_btree_key_addr(cur, 1, cblock);
    xfs_btree_copy_keys(cur, kp, ckp, numrecs);

    pp = xfs_btree_ptr_addr(cur, 1, block);
    cpp = xfs_btree_ptr_addr(cur, 1, cblock);
#ifdef DEBUG
    for (i = 0; i < numrecs; i++) {
        int     error;

        error = xfs_btree_check_ptr(cur, cpp, i, level - 1);
        if (error) {
            XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
            return error;
        }
    }
#endif
    xfs_btree_copy_ptrs(cur, pp, cpp, numrecs);

    cur->bc_ops->free_block(cur, cbp);
    XFS_BTREE_STATS_INC(cur, free);

    cur->bc_bufs[level - 1] = NULL;
    be16_add_cpu(&block->bb_level, -1);
    xfs_trans_log_inode(cur->bc_tp, ip,
        XFS_ILOG_CORE | xfs_ilog_fbroot(cur->bc_private.b.whichfork));
    cur->bc_nlevels--;
out0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    return 0;
}

/*
 * Kill the current root node, and replace it with it's only child node.
 */
STATIC int
xfs_btree_kill_root(
    struct xfs_btree_cur    *cur,
    struct xfs_buf      *bp,
    int         level,
    union xfs_btree_ptr *newroot)
{
    int         error;

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_STATS_INC(cur, killroot);

    /*
     * Update the root pointer, decreasing the level by 1 and then
     * free the old root.
     */
    cur->bc_ops->set_root(cur, newroot, -1);

    error = cur->bc_ops->free_block(cur, bp);
    if (error) {
        XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
        return error;
    }

    XFS_BTREE_STATS_INC(cur, free);

    cur->bc_bufs[level] = NULL;
    cur->bc_ra[level] = 0;
    cur->bc_nlevels--;

    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    return 0;
}

STATIC int
xfs_btree_dec_cursor(
    struct xfs_btree_cur    *cur,
    int         level,
    int         *stat)
{
    int         error;
    int         i;

    if (level > 0) {
        error = xfs_btree_decrement(cur, level, &i);
        if (error)
            return error;
    }

    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = 1;
    return 0;
}

/*
 * Single level of the btree record deletion routine.
 * Delete record pointed to by cur/level.
 * Remove the record from its block then rebalance the tree.
 * Return 0 for error, 1 for done, 2 to go on to the next level.
 */
STATIC int                  /* error */
xfs_btree_delrec(
    struct xfs_btree_cur    *cur,       /* btree cursor */
    int         level,      /* level removing record from */
    int         *stat)      /* fail/done/go-on */
{
    struct xfs_btree_block  *block;     /* btree block */
    union xfs_btree_ptr cptr;       /* current block ptr */
    struct xfs_buf      *bp;        /* buffer for block */
    int         error;      /* error return value */
    int         i;      /* loop counter */
    union xfs_btree_key key;        /* storage for keyp */
    union xfs_btree_key *keyp = &key;   /* passed to the next level */
    union xfs_btree_ptr lptr;       /* left sibling block ptr */
    struct xfs_buf      *lbp;       /* left buffer pointer */
    struct xfs_btree_block  *left;      /* left btree block */
    int         lrecs = 0;  /* left record count */
    int         ptr;        /* key/record index */
    union xfs_btree_ptr rptr;       /* right sibling block ptr */
    struct xfs_buf      *rbp;       /* right buffer pointer */
    struct xfs_btree_block  *right;     /* right btree block */
    struct xfs_btree_block  *rrblock;   /* right-right btree block */
    struct xfs_buf      *rrbp;      /* right-right buffer pointer */
    int         rrecs = 0;  /* right record count */
    struct xfs_btree_cur    *tcur;      /* temporary btree cursor */
    int         numrecs;    /* temporary numrec count */

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);
    XFS_BTREE_TRACE_ARGI(cur, level);

    tcur = NULL;

    /* Get the index of the entry being deleted, check for nothing there. */
    ptr = cur->bc_ptrs[level];
    if (ptr == 0) {
        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
        *stat = 0;
        return 0;
    }

    /* Get the buffer & block containing the record or key/ptr. */
    block = xfs_btree_get_block(cur, level, &bp);
    numrecs = xfs_btree_get_numrecs(block);

#ifdef DEBUG
    error = xfs_btree_check_block(cur, block, level, bp);
    if (error)
        goto error0;
#endif

    /* Fail if we're off the end of the block. */
    if (ptr > numrecs) {
        XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
        *stat = 0;
        return 0;
    }

    XFS_BTREE_STATS_INC(cur, delrec);
    XFS_BTREE_STATS_ADD(cur, moves, numrecs - ptr);

    /* Excise the entries being deleted. */
    if (level > 0) {
        /* It's a nonleaf. operate on keys and ptrs */
        union xfs_btree_key *lkp;
        union xfs_btree_ptr *lpp;

        lkp = xfs_btree_key_addr(cur, ptr + 1, block);
        lpp = xfs_btree_ptr_addr(cur, ptr + 1, block);

#ifdef DEBUG
        for (i = 0; i < numrecs - ptr; i++) {
            error = xfs_btree_check_ptr(cur, lpp, i, level);
            if (error)
                goto error0;
        }
#endif

        if (ptr < numrecs) {
            xfs_btree_shift_keys(cur, lkp, -1, numrecs - ptr);
            xfs_btree_shift_ptrs(cur, lpp, -1, numrecs - ptr);
            xfs_btree_log_keys(cur, bp, ptr, numrecs - 1);
            xfs_btree_log_ptrs(cur, bp, ptr, numrecs - 1);
        }

        /*
         * If it's the first record in the block, we'll need to pass a
         * key up to the next level (updkey).
         */
        if (ptr == 1)
            keyp = xfs_btree_key_addr(cur, 1, block);
    } else {
        /* It's a leaf. operate on records */
        if (ptr < numrecs) {
            xfs_btree_shift_recs(cur,
                xfs_btree_rec_addr(cur, ptr + 1, block),
                -1, numrecs - ptr);
            xfs_btree_log_recs(cur, bp, ptr, numrecs - 1);
        }

        /*
         * If it's the first record in the block, we'll need a key
         * structure to pass up to the next level (updkey).
         */
        if (ptr == 1) {
            cur->bc_ops->init_key_from_rec(&key,
                    xfs_btree_rec_addr(cur, 1, block));
            keyp = &key;
        }
    }

    /*
     * Decrement and log the number of entries in the block.
     */
    xfs_btree_set_numrecs(block, --numrecs);
    xfs_btree_log_block(cur, bp, XFS_BB_NUMRECS);

    /*
     * If we are tracking the last record in the tree and
     * we are at the far right edge of the tree, update it.
     */
    if (xfs_btree_is_lastrec(cur, block, level)) {
        cur->bc_ops->update_lastrec(cur, block, NULL,
                        ptr, LASTREC_DELREC);
    }

    /*
     * We're at the root level.  First, shrink the root block in-memory.
     * Try to get rid of the next level down.  If we can't then there's
     * nothing left to do.
     */
    if (level == cur->bc_nlevels - 1) {
        if (cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) {
            xfs_iroot_realloc(cur->bc_private.b.ip, -1,
                      cur->bc_private.b.whichfork);

            error = xfs_btree_kill_iroot(cur);
            if (error)
                goto error0;

            error = xfs_btree_dec_cursor(cur, level, stat);
            if (error)
                goto error0;
            *stat = 1;
            return 0;
        }

        /*
         * If this is the root level, and there's only one entry left,
         * and it's NOT the leaf level, then we can get rid of this
         * level.
         */
        if (numrecs == 1 && level > 0) {
            union xfs_btree_ptr *pp;
            /*
             * pp is still set to the first pointer in the block.
             * Make it the new root of the btree.
             */
            pp = xfs_btree_ptr_addr(cur, 1, block);
            error = xfs_btree_kill_root(cur, bp, level, pp);
            if (error)
                goto error0;
        } else if (level > 0) {
            error = xfs_btree_dec_cursor(cur, level, stat);
            if (error)
                goto error0;
        }
        *stat = 1;
        return 0;
    }

    /*
     * If we deleted the leftmost entry in the block, update the
     * key values above us in the tree.
     */
    if (ptr == 1) {
        error = xfs_btree_updkey(cur, keyp, level + 1);
        if (error)
            goto error0;
    }

    /*
     * If the number of records remaining in the block is at least
     * the minimum, we're done.
     */
    if (numrecs >= cur->bc_ops->get_minrecs(cur, level)) {
        error = xfs_btree_dec_cursor(cur, level, stat);
        if (error)
            goto error0;
        return 0;
    }

    /*
     * Otherwise, we have to move some records around to keep the
     * tree balanced.  Look at the left and right sibling blocks to
     * see if we can re-balance by moving only one record.
     */
    xfs_btree_get_sibling(cur, block, &rptr, XFS_BB_RIGHTSIB);
    xfs_btree_get_sibling(cur, block, &lptr, XFS_BB_LEFTSIB);

    if (cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) {
        /*
         * One child of root, need to get a chance to copy its contents
         * into the root and delete it. Can't go up to next level,
         * there's nothing to delete there.
         */
        if (xfs_btree_ptr_is_null(cur, &rptr) &&
            xfs_btree_ptr_is_null(cur, &lptr) &&
            level == cur->bc_nlevels - 2) {
            error = xfs_btree_kill_iroot(cur);
            if (!error)
                error = xfs_btree_dec_cursor(cur, level, stat);
            if (error)
                goto error0;
            return 0;
        }
    }

    ASSERT(!xfs_btree_ptr_is_null(cur, &rptr) ||
           !xfs_btree_ptr_is_null(cur, &lptr));

    /*
     * Duplicate the cursor so our btree manipulations here won't
     * disrupt the next level up.
     */
    error = xfs_btree_dup_cursor(cur, &tcur);
    if (error)
        goto error0;

    /*
     * If there's a right sibling, see if it's ok to shift an entry
     * out of it.
     */
    if (!xfs_btree_ptr_is_null(cur, &rptr)) {
        /*
         * Move the temp cursor to the last entry in the next block.
         * Actually any entry but the first would suffice.
         */
        i = xfs_btree_lastrec(tcur, level);
        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

        error = xfs_btree_increment(tcur, level, &i);
        if (error)
            goto error0;
        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

        i = xfs_btree_lastrec(tcur, level);
        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

        /* Grab a pointer to the block. */
        right = xfs_btree_get_block(tcur, level, &rbp);
#ifdef DEBUG
        error = xfs_btree_check_block(tcur, right, level, rbp);
        if (error)
            goto error0;
#endif
        /* Grab the current block number, for future use. */
        xfs_btree_get_sibling(tcur, right, &cptr, XFS_BB_LEFTSIB);

        /*
         * If right block is full enough so that removing one entry
         * won't make it too empty, and left-shifting an entry out
         * of right to us works, we're done.
         */
        if (xfs_btree_get_numrecs(right) - 1 >=
            cur->bc_ops->get_minrecs(tcur, level)) {
            error = xfs_btree_lshift(tcur, level, &i);
            if (error)
                goto error0;
            if (i) {
                ASSERT(xfs_btree_get_numrecs(block) >=
                       cur->bc_ops->get_minrecs(tcur, level));

                xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
                tcur = NULL;

                error = xfs_btree_dec_cursor(cur, level, stat);
                if (error)
                    goto error0;
                return 0;
            }
        }

        /*
         * Otherwise, grab the number of records in right for
         * future reference, and fix up the temp cursor to point
         * to our block again (last record).
         */
        rrecs = xfs_btree_get_numrecs(right);
        if (!xfs_btree_ptr_is_null(cur, &lptr)) {
            i = xfs_btree_firstrec(tcur, level);
            XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

            error = xfs_btree_decrement(tcur, level, &i);
            if (error)
                goto error0;
            XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
        }
    }

    /*
     * If there's a left sibling, see if it's ok to shift an entry
     * out of it.
     */
    if (!xfs_btree_ptr_is_null(cur, &lptr)) {
        /*
         * Move the temp cursor to the first entry in the
         * previous block.
         */
        i = xfs_btree_firstrec(tcur, level);
        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

        error = xfs_btree_decrement(tcur, level, &i);
        if (error)
            goto error0;
        i = xfs_btree_firstrec(tcur, level);
        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);

        /* Grab a pointer to the block. */
        left = xfs_btree_get_block(tcur, level, &lbp);
#ifdef DEBUG
        error = xfs_btree_check_block(cur, left, level, lbp);
        if (error)
            goto error0;
#endif
        /* Grab the current block number, for future use. */
        xfs_btree_get_sibling(tcur, left, &cptr, XFS_BB_RIGHTSIB);

        /*
         * If left block is full enough so that removing one entry
         * won't make it too empty, and right-shifting an entry out
         * of left to us works, we're done.
         */
        if (xfs_btree_get_numrecs(left) - 1 >=
            cur->bc_ops->get_minrecs(tcur, level)) {
            error = xfs_btree_rshift(tcur, level, &i);
            if (error)
                goto error0;
            if (i) {
                ASSERT(xfs_btree_get_numrecs(block) >=
                       cur->bc_ops->get_minrecs(tcur, level));
                xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
                tcur = NULL;
                if (level == 0)
                    cur->bc_ptrs[0]++;
                XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
                *stat = 1;
                return 0;
            }
        }

        /*
         * Otherwise, grab the number of records in right for
         * future reference.
         */
        lrecs = xfs_btree_get_numrecs(left);
    }

    /* Delete the temp cursor, we're done with it. */
    xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
    tcur = NULL;

    /* If here, we need to do a join to keep the tree balanced. */
    ASSERT(!xfs_btree_ptr_is_null(cur, &cptr));

    if (!xfs_btree_ptr_is_null(cur, &lptr) &&
        lrecs + xfs_btree_get_numrecs(block) <=
            cur->bc_ops->get_maxrecs(cur, level)) {
        /*
         * Set "right" to be the starting block,
         * "left" to be the left neighbor.
         */
        rptr = cptr;
        right = block;
        rbp = bp;
        error = xfs_btree_read_buf_block(cur, &lptr, level,
                            0, &left, &lbp);
        if (error)
            goto error0;

    /*
     * If that won't work, see if we can join with the right neighbor block.
     */
    } else if (!xfs_btree_ptr_is_null(cur, &rptr) &&
           rrecs + xfs_btree_get_numrecs(block) <=
            cur->bc_ops->get_maxrecs(cur, level)) {
        /*
         * Set "left" to be the starting block,
         * "right" to be the right neighbor.
         */
        lptr = cptr;
        left = block;
        lbp = bp;
        error = xfs_btree_read_buf_block(cur, &rptr, level,
                            0, &right, &rbp);
        if (error)
            goto error0;

    /*
     * Otherwise, we can't fix the imbalance.
     * Just return.  This is probably a logic error, but it's not fatal.
     */
    } else {
        error = xfs_btree_dec_cursor(cur, level, stat);
        if (error)
            goto error0;
        return 0;
    }

    rrecs = xfs_btree_get_numrecs(right);
    lrecs = xfs_btree_get_numrecs(left);

    /*
     * We're now going to join "left" and "right" by moving all the stuff
     * in "right" to "left" and deleting "right".
     */
    XFS_BTREE_STATS_ADD(cur, moves, rrecs);
    if (level > 0) {
        /* It's a non-leaf.  Move keys and pointers. */
        union xfs_btree_key *lkp;   /* left btree key */
        union xfs_btree_ptr *lpp;   /* left address pointer */
        union xfs_btree_key *rkp;   /* right btree key */
        union xfs_btree_ptr *rpp;   /* right address pointer */

        lkp = xfs_btree_key_addr(cur, lrecs + 1, left);
        lpp = xfs_btree_ptr_addr(cur, lrecs + 1, left);
        rkp = xfs_btree_key_addr(cur, 1, right);
        rpp = xfs_btree_ptr_addr(cur, 1, right);
#ifdef DEBUG
        for (i = 1; i < rrecs; i++) {
            error = xfs_btree_check_ptr(cur, rpp, i, level);
            if (error)
                goto error0;
        }
#endif
        xfs_btree_copy_keys(cur, lkp, rkp, rrecs);
        xfs_btree_copy_ptrs(cur, lpp, rpp, rrecs);

        xfs_btree_log_keys(cur, lbp, lrecs + 1, lrecs + rrecs);
        xfs_btree_log_ptrs(cur, lbp, lrecs + 1, lrecs + rrecs);
    } else {
        /* It's a leaf.  Move records.  */
        union xfs_btree_rec *lrp;   /* left record pointer */
        union xfs_btree_rec *rrp;   /* right record pointer */

        lrp = xfs_btree_rec_addr(cur, lrecs + 1, left);
        rrp = xfs_btree_rec_addr(cur, 1, right);

        xfs_btree_copy_recs(cur, lrp, rrp, rrecs);
        xfs_btree_log_recs(cur, lbp, lrecs + 1, lrecs + rrecs);
    }

    XFS_BTREE_STATS_INC(cur, join);

    /*
     * Fix up the number of records and right block pointer in the
     * surviving block, and log it.
     */
    xfs_btree_set_numrecs(left, lrecs + rrecs);
    xfs_btree_get_sibling(cur, right, &cptr, XFS_BB_RIGHTSIB),
    xfs_btree_set_sibling(cur, left, &cptr, XFS_BB_RIGHTSIB);
    xfs_btree_log_block(cur, lbp, XFS_BB_NUMRECS | XFS_BB_RIGHTSIB);

    /* If there is a right sibling, point it to the remaining block. */
    xfs_btree_get_sibling(cur, left, &cptr, XFS_BB_RIGHTSIB);
    if (!xfs_btree_ptr_is_null(cur, &cptr)) {
        error = xfs_btree_read_buf_block(cur, &cptr, level,
                            0, &rrblock, &rrbp);
        if (error)
            goto error0;
        xfs_btree_set_sibling(cur, rrblock, &lptr, XFS_BB_LEFTSIB);
        xfs_btree_log_block(cur, rrbp, XFS_BB_LEFTSIB);
    }

    /* Free the deleted block. */
    error = cur->bc_ops->free_block(cur, rbp);
    if (error)
        goto error0;
    XFS_BTREE_STATS_INC(cur, free);

    /*
     * If we joined with the left neighbor, set the buffer in the
     * cursor to the left block, and fix up the index.
     */
    if (bp != lbp) {
        cur->bc_bufs[level] = lbp;
        cur->bc_ptrs[level] += lrecs;
        cur->bc_ra[level] = 0;
    }
    /*
     * If we joined with the right neighbor and there's a level above
     * us, increment the cursor at that level.
     */
    else if ((cur->bc_flags & XFS_BTREE_ROOT_IN_INODE) ||
           (level + 1 < cur->bc_nlevels)) {
        error = xfs_btree_increment(cur, level + 1, &i);
        if (error)
            goto error0;
    }

    /*
     * Readjust the ptr at this level if it's not a leaf, since it's
     * still pointing at the deletion point, which makes the cursor
     * inconsistent.  If this makes the ptr 0, the caller fixes it up.
     * We can't use decrement because it would change the next level up.
     */
    if (level > 0)
        cur->bc_ptrs[level]--;

    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    /* Return value means the next level up has something to do. */
    *stat = 2;
    return 0;

error0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
    if (tcur)
        xfs_btree_del_cursor(tcur, XFS_BTREE_ERROR);
    return error;
}

/*
 * Delete the record pointed to by cur.
 * The cursor refers to the place where the record was (could be inserted)
 * when the operation returns.
 */
int                 /* error */
xfs_btree_delete(
    struct xfs_btree_cur    *cur,
    int         *stat)  /* success/failure */
{
    int         error;  /* error return value */
    int         level;
    int         i;

    XFS_BTREE_TRACE_CURSOR(cur, XBT_ENTRY);

    /*
     * Go up the tree, starting at leaf level.
     *
     * If 2 is returned then a join was done; go to the next level.
     * Otherwise we are done.
     */
    for (level = 0, i = 2; i == 2; level++) {
        error = xfs_btree_delrec(cur, level, &i);
        if (error)
            goto error0;
    }

    if (i == 0) {
        for (level = 1; level < cur->bc_nlevels; level++) {
            if (cur->bc_ptrs[level] == 0) {
                error = xfs_btree_decrement(cur, level, &i);
                if (error)
                    goto error0;
                break;
            }
        }
    }

    XFS_BTREE_TRACE_CURSOR(cur, XBT_EXIT);
    *stat = i;
    return 0;
error0:
    XFS_BTREE_TRACE_CURSOR(cur, XBT_ERROR);
    return error;
}

/*
 * Get the data from the pointed-to record.
 */
int                 /* error */
xfs_btree_get_rec(
    struct xfs_btree_cur    *cur,   /* btree cursor */
    union xfs_btree_rec **recp, /* output: btree record */
    int         *stat)  /* output: success/failure */
{
    struct xfs_btree_block  *block; /* btree block */
    struct xfs_buf      *bp;    /* buffer pointer */
    int         ptr;    /* record number */
#ifdef DEBUG
    int         error;  /* error return value */
#endif

    ptr = cur->bc_ptrs[0];
    block = xfs_btree_get_block(cur, 0, &bp);

#ifdef DEBUG
    error = xfs_btree_check_block(cur, block, 0, bp);
    if (error)
        return error;
#endif

    /*
     * Off the right end or left end, return failure.
     */
    if (ptr > xfs_btree_get_numrecs(block) || ptr <= 0) {
        *stat = 0;
        return 0;
    }

    /*
     * Point to the record and extract its data.
     */
    *recp = xfs_btree_rec_addr(cur, ptr, block);
    *stat = 1;
    return 0;
}