Avoid beyond bounds copy while caching ACL

[zen-stable.git] / fs / xfs / xfs_dir2_node.c

/*
 * Copyright (c) 2000-2005 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_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_mount.h"
#include "xfs_da_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_bmap.h"
#include "xfs_dir2_format.h"
#include "xfs_dir2_priv.h"
#include "xfs_error.h"
#include "xfs_trace.h"

/*
 * Function declarations.
 */
static void xfs_dir2_free_log_header(xfs_trans_t *tp, xfs_dabuf_t *bp);
static int xfs_dir2_leafn_add(xfs_dabuf_t *bp, xfs_da_args_t *args, int index);
#ifdef DEBUG
static void xfs_dir2_leafn_check(xfs_inode_t *dp, xfs_dabuf_t *bp);
#else
#define xfs_dir2_leafn_check(dp, bp)
#endif
static void xfs_dir2_leafn_moveents(xfs_da_args_t *args, xfs_dabuf_t *bp_s,
                                    int start_s, xfs_dabuf_t *bp_d, int start_d,
                                    int count);
static void xfs_dir2_leafn_rebalance(xfs_da_state_t *state,
                                     xfs_da_state_blk_t *blk1,
                                     xfs_da_state_blk_t *blk2);
static int xfs_dir2_leafn_remove(xfs_da_args_t *args, xfs_dabuf_t *bp,
                                 int index, xfs_da_state_blk_t *dblk,
                                 int *rval);
static int xfs_dir2_node_addname_int(xfs_da_args_t *args,
                                     xfs_da_state_blk_t *fblk);

/*
 * Log entries from a freespace block.
 */
STATIC void
xfs_dir2_free_log_bests(
        xfs_trans_t             *tp,            /* transaction pointer */
        xfs_dabuf_t             *bp,            /* freespace buffer */
        int                     first,          /* first entry to log */
        int                     last)           /* last entry to log */
{
        xfs_dir2_free_t         *free;          /* freespace structure */

        free = bp->data;
        ASSERT(free->hdr.magic == cpu_to_be32(XFS_DIR2_FREE_MAGIC));
        xfs_da_log_buf(tp, bp,
                (uint)((char *)&free->bests[first] - (char *)free),
                (uint)((char *)&free->bests[last] - (char *)free +
                       sizeof(free->bests[0]) - 1));
}

/*
 * Log header from a freespace block.
 */
static void
xfs_dir2_free_log_header(
        xfs_trans_t             *tp,            /* transaction pointer */
        xfs_dabuf_t             *bp)            /* freespace buffer */
{
        xfs_dir2_free_t         *free;          /* freespace structure */

        free = bp->data;
        ASSERT(free->hdr.magic == cpu_to_be32(XFS_DIR2_FREE_MAGIC));
        xfs_da_log_buf(tp, bp, (uint)((char *)&free->hdr - (char *)free),
                (uint)(sizeof(xfs_dir2_free_hdr_t) - 1));
}

/*
 * Convert a leaf-format directory to a node-format directory.
 * We need to change the magic number of the leaf block, and copy
 * the freespace table out of the leaf block into its own block.
 */
int                                             /* error */
xfs_dir2_leaf_to_node(
        xfs_da_args_t           *args,          /* operation arguments */
        xfs_dabuf_t             *lbp)           /* leaf buffer */
{
        xfs_inode_t             *dp;            /* incore directory inode */
        int                     error;          /* error return value */
        xfs_dabuf_t             *fbp;           /* freespace buffer */
        xfs_dir2_db_t           fdb;            /* freespace block number */
        xfs_dir2_free_t         *free;          /* freespace structure */
        __be16                  *from;          /* pointer to freespace entry */
        int                     i;              /* leaf freespace index */
        xfs_dir2_leaf_t         *leaf;          /* leaf structure */
        xfs_dir2_leaf_tail_t    *ltp;           /* leaf tail structure */
        xfs_mount_t             *mp;            /* filesystem mount point */
        int                     n;              /* count of live freespc ents */
        xfs_dir2_data_off_t     off;            /* freespace entry value */
        __be16                  *to;            /* pointer to freespace entry */
        xfs_trans_t             *tp;            /* transaction pointer */

        trace_xfs_dir2_leaf_to_node(args);

        dp = args->dp;
        mp = dp->i_mount;
        tp = args->trans;
        /*
         * Add a freespace block to the directory.
         */
        if ((error = xfs_dir2_grow_inode(args, XFS_DIR2_FREE_SPACE, &fdb))) {
                return error;
        }
        ASSERT(fdb == XFS_DIR2_FREE_FIRSTDB(mp));
        /*
         * Get the buffer for the new freespace block.
         */
        if ((error = xfs_da_get_buf(tp, dp, xfs_dir2_db_to_da(mp, fdb), -1, &fbp,
                        XFS_DATA_FORK))) {
                return error;
        }
        ASSERT(fbp != NULL);
        free = fbp->data;
        leaf = lbp->data;
        ltp = xfs_dir2_leaf_tail_p(mp, leaf);
        /*
         * Initialize the freespace block header.
         */
        free->hdr.magic = cpu_to_be32(XFS_DIR2_FREE_MAGIC);
        free->hdr.firstdb = 0;
        ASSERT(be32_to_cpu(ltp->bestcount) <= (uint)dp->i_d.di_size / mp->m_dirblksize);
        free->hdr.nvalid = ltp->bestcount;
        /*
         * Copy freespace entries from the leaf block to the new block.
         * Count active entries.
         */
        for (i = n = 0, from = xfs_dir2_leaf_bests_p(ltp), to = free->bests;
             i < be32_to_cpu(ltp->bestcount); i++, from++, to++) {
                if ((off = be16_to_cpu(*from)) != NULLDATAOFF)
                        n++;
                *to = cpu_to_be16(off);
        }
        free->hdr.nused = cpu_to_be32(n);
        leaf->hdr.info.magic = cpu_to_be16(XFS_DIR2_LEAFN_MAGIC);
        /*
         * Log everything.
         */
        xfs_dir2_leaf_log_header(tp, lbp);
        xfs_dir2_free_log_header(tp, fbp);
        xfs_dir2_free_log_bests(tp, fbp, 0, be32_to_cpu(free->hdr.nvalid) - 1);
        xfs_da_buf_done(fbp);
        xfs_dir2_leafn_check(dp, lbp);
        return 0;
}

/*
 * Add a leaf entry to a leaf block in a node-form directory.
 * The other work necessary is done from the caller.
 */
static int                                      /* error */
xfs_dir2_leafn_add(
        xfs_dabuf_t             *bp,            /* leaf buffer */
        xfs_da_args_t           *args,          /* operation arguments */
        int                     index)          /* insertion pt for new entry */
{
        int                     compact;        /* compacting stale leaves */
        xfs_inode_t             *dp;            /* incore directory inode */
        int                     highstale;      /* next stale entry */
        xfs_dir2_leaf_t         *leaf;          /* leaf structure */
        xfs_dir2_leaf_entry_t   *lep;           /* leaf entry */
        int                     lfloghigh;      /* high leaf entry logging */
        int                     lfloglow;       /* low leaf entry logging */
        int                     lowstale;       /* previous stale entry */
        xfs_mount_t             *mp;            /* filesystem mount point */
        xfs_trans_t             *tp;            /* transaction pointer */

        trace_xfs_dir2_leafn_add(args, index);

        dp = args->dp;
        mp = dp->i_mount;
        tp = args->trans;
        leaf = bp->data;

        /*
         * Quick check just to make sure we are not going to index
         * into other peoples memory
         */
        if (index < 0)
                return XFS_ERROR(EFSCORRUPTED);

        /*
         * If there are already the maximum number of leaf entries in
         * the block, if there are no stale entries it won't fit.
         * Caller will do a split.  If there are stale entries we'll do
         * a compact.
         */

        if (be16_to_cpu(leaf->hdr.count) == xfs_dir2_max_leaf_ents(mp)) {
                if (!leaf->hdr.stale)
                        return XFS_ERROR(ENOSPC);
                compact = be16_to_cpu(leaf->hdr.stale) > 1;
        } else
                compact = 0;
        ASSERT(index == 0 || be32_to_cpu(leaf->ents[index - 1].hashval) <= args->hashval);
        ASSERT(index == be16_to_cpu(leaf->hdr.count) ||
               be32_to_cpu(leaf->ents[index].hashval) >= args->hashval);

        if (args->op_flags & XFS_DA_OP_JUSTCHECK)
                return 0;

        /*
         * Compact out all but one stale leaf entry.  Leaves behind
         * the entry closest to index.
         */
        if (compact) {
                xfs_dir2_leaf_compact_x1(bp, &index, &lowstale, &highstale,
                        &lfloglow, &lfloghigh);
        }
        /*
         * Set impossible logging indices for this case.
         */
        else if (leaf->hdr.stale) {
                lfloglow = be16_to_cpu(leaf->hdr.count);
                lfloghigh = -1;
        }

        /*
         * Insert the new entry, log everything.
         */
        lep = xfs_dir2_leaf_find_entry(leaf, index, compact, lowstale,
                                       highstale, &lfloglow, &lfloghigh);

        lep->hashval = cpu_to_be32(args->hashval);
        lep->address = cpu_to_be32(xfs_dir2_db_off_to_dataptr(mp,
                                args->blkno, args->index));
        xfs_dir2_leaf_log_header(tp, bp);
        xfs_dir2_leaf_log_ents(tp, bp, lfloglow, lfloghigh);
        xfs_dir2_leafn_check(dp, bp);
        return 0;
}

#ifdef DEBUG
/*
 * Check internal consistency of a leafn block.
 */
void
xfs_dir2_leafn_check(
        xfs_inode_t     *dp,                    /* incore directory inode */
        xfs_dabuf_t     *bp)                    /* leaf buffer */
{
        int             i;                      /* leaf index */
        xfs_dir2_leaf_t *leaf;                  /* leaf structure */
        xfs_mount_t     *mp;                    /* filesystem mount point */
        int             stale;                  /* count of stale leaves */

        leaf = bp->data;
        mp = dp->i_mount;
        ASSERT(leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAFN_MAGIC));
        ASSERT(be16_to_cpu(leaf->hdr.count) <= xfs_dir2_max_leaf_ents(mp));
        for (i = stale = 0; i < be16_to_cpu(leaf->hdr.count); i++) {
                if (i + 1 < be16_to_cpu(leaf->hdr.count)) {
                        ASSERT(be32_to_cpu(leaf->ents[i].hashval) <=
                               be32_to_cpu(leaf->ents[i + 1].hashval));
                }
                if (leaf->ents[i].address == cpu_to_be32(XFS_DIR2_NULL_DATAPTR))
                        stale++;
        }
        ASSERT(be16_to_cpu(leaf->hdr.stale) == stale);
}
#endif  /* DEBUG */

/*
 * Return the last hash value in the leaf.
 * Stale entries are ok.
 */
xfs_dahash_t                                    /* hash value */
xfs_dir2_leafn_lasthash(
        xfs_dabuf_t     *bp,                    /* leaf buffer */
        int             *count)                 /* count of entries in leaf */
{
        xfs_dir2_leaf_t *leaf;                  /* leaf structure */

        leaf = bp->data;
        ASSERT(leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAFN_MAGIC));
        if (count)
                *count = be16_to_cpu(leaf->hdr.count);
        if (!leaf->hdr.count)
                return 0;
        return be32_to_cpu(leaf->ents[be16_to_cpu(leaf->hdr.count) - 1].hashval);
}

/*
 * Look up a leaf entry for space to add a name in a node-format leaf block.
 * The extrablk in state is a freespace block.
 */
STATIC int
xfs_dir2_leafn_lookup_for_addname(
        xfs_dabuf_t             *bp,            /* leaf buffer */
        xfs_da_args_t           *args,          /* operation arguments */
        int                     *indexp,        /* out: leaf entry index */
        xfs_da_state_t          *state)         /* state to fill in */
{
        xfs_dabuf_t             *curbp = NULL;  /* current data/free buffer */
        xfs_dir2_db_t           curdb = -1;     /* current data block number */
        xfs_dir2_db_t           curfdb = -1;    /* current free block number */
        xfs_inode_t             *dp;            /* incore directory inode */
        int                     error;          /* error return value */
        int                     fi;             /* free entry index */
        xfs_dir2_free_t         *free = NULL;   /* free block structure */
        int                     index;          /* leaf entry index */
        xfs_dir2_leaf_t         *leaf;          /* leaf structure */
        int                     length;         /* length of new data entry */
        xfs_dir2_leaf_entry_t   *lep;           /* leaf entry */
        xfs_mount_t             *mp;            /* filesystem mount point */
        xfs_dir2_db_t           newdb;          /* new data block number */
        xfs_dir2_db_t           newfdb;         /* new free block number */
        xfs_trans_t             *tp;            /* transaction pointer */

        dp = args->dp;
        tp = args->trans;
        mp = dp->i_mount;
        leaf = bp->data;
        ASSERT(leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAFN_MAGIC));
#ifdef __KERNEL__
        ASSERT(be16_to_cpu(leaf->hdr.count) > 0);
#endif
        xfs_dir2_leafn_check(dp, bp);
        /*
         * Look up the hash value in the leaf entries.
         */
        index = xfs_dir2_leaf_search_hash(args, bp);
        /*
         * Do we have a buffer coming in?
         */
        if (state->extravalid) {
                /* If so, it's a free block buffer, get the block number. */
                curbp = state->extrablk.bp;
                curfdb = state->extrablk.blkno;
                free = curbp->data;
                ASSERT(free->hdr.magic == cpu_to_be32(XFS_DIR2_FREE_MAGIC));
        }
        length = xfs_dir2_data_entsize(args->namelen);
        /*
         * Loop over leaf entries with the right hash value.
         */
        for (lep = &leaf->ents[index]; index < be16_to_cpu(leaf->hdr.count) &&
                                be32_to_cpu(lep->hashval) == args->hashval;
                                lep++, index++) {
                /*
                 * Skip stale leaf entries.
                 */
                if (be32_to_cpu(lep->address) == XFS_DIR2_NULL_DATAPTR)
                        continue;
                /*
                 * Pull the data block number from the entry.
                 */
                newdb = xfs_dir2_dataptr_to_db(mp, be32_to_cpu(lep->address));
                /*
                 * For addname, we're looking for a place to put the new entry.
                 * We want to use a data block with an entry of equal
                 * hash value to ours if there is one with room.
                 *
                 * If this block isn't the data block we already have
                 * in hand, take a look at it.
                 */
                if (newdb != curdb) {
                        curdb = newdb;
                        /*
                         * Convert the data block to the free block
                         * holding its freespace information.
                         */
                        newfdb = xfs_dir2_db_to_fdb(mp, newdb);
                        /*
                         * If it's not the one we have in hand, read it in.
                         */
                        if (newfdb != curfdb) {
                                /*
                                 * If we had one before, drop it.
                                 */
                                if (curbp)
                                        xfs_da_brelse(tp, curbp);
                                /*
                                 * Read the free block.
                                 */
                                error = xfs_da_read_buf(tp, dp,
                                                xfs_dir2_db_to_da(mp, newfdb),
                                                -1, &curbp, XFS_DATA_FORK);
                                if (error)
                                        return error;
                                free = curbp->data;
                                ASSERT(be32_to_cpu(free->hdr.magic) ==
                                        XFS_DIR2_FREE_MAGIC);
                                ASSERT((be32_to_cpu(free->hdr.firstdb) %
                                        xfs_dir2_free_max_bests(mp)) == 0);
                                ASSERT(be32_to_cpu(free->hdr.firstdb) <= curdb);
                                ASSERT(curdb < be32_to_cpu(free->hdr.firstdb) +
                                        be32_to_cpu(free->hdr.nvalid));
                        }
                        /*
                         * Get the index for our entry.
                         */
                        fi = xfs_dir2_db_to_fdindex(mp, curdb);
                        /*
                         * If it has room, return it.
                         */
                        if (unlikely(free->bests[fi] ==
                            cpu_to_be16(NULLDATAOFF))) {
                                XFS_ERROR_REPORT("xfs_dir2_leafn_lookup_int",
                                                        XFS_ERRLEVEL_LOW, mp);
                                if (curfdb != newfdb)
                                        xfs_da_brelse(tp, curbp);
                                return XFS_ERROR(EFSCORRUPTED);
                        }
                        curfdb = newfdb;
                        if (be16_to_cpu(free->bests[fi]) >= length)
                                goto out;
                }
        }
        /* Didn't find any space */
        fi = -1;
out:
        ASSERT(args->op_flags & XFS_DA_OP_OKNOENT);
        if (curbp) {
                /* Giving back a free block. */
                state->extravalid = 1;
                state->extrablk.bp = curbp;
                state->extrablk.index = fi;
                state->extrablk.blkno = curfdb;
                state->extrablk.magic = XFS_DIR2_FREE_MAGIC;
        } else {
                state->extravalid = 0;
        }
        /*
         * Return the index, that will be the insertion point.
         */
        *indexp = index;
        return XFS_ERROR(ENOENT);
}

/*
 * Look up a leaf entry in a node-format leaf block.
 * The extrablk in state a data block.
 */
STATIC int
xfs_dir2_leafn_lookup_for_entry(
        xfs_dabuf_t             *bp,            /* leaf buffer */
        xfs_da_args_t           *args,          /* operation arguments */
        int                     *indexp,        /* out: leaf entry index */
        xfs_da_state_t          *state)         /* state to fill in */
{
        xfs_dabuf_t             *curbp = NULL;  /* current data/free buffer */
        xfs_dir2_db_t           curdb = -1;     /* current data block number */
        xfs_dir2_data_entry_t   *dep;           /* data block entry */
        xfs_inode_t             *dp;            /* incore directory inode */
        int                     error;          /* error return value */
        int                     index;          /* leaf entry index */
        xfs_dir2_leaf_t         *leaf;          /* leaf structure */
        xfs_dir2_leaf_entry_t   *lep;           /* leaf entry */
        xfs_mount_t             *mp;            /* filesystem mount point */
        xfs_dir2_db_t           newdb;          /* new data block number */
        xfs_trans_t             *tp;            /* transaction pointer */
        enum xfs_dacmp          cmp;            /* comparison result */

        dp = args->dp;
        tp = args->trans;
        mp = dp->i_mount;
        leaf = bp->data;
        ASSERT(leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAFN_MAGIC));
#ifdef __KERNEL__
        ASSERT(be16_to_cpu(leaf->hdr.count) > 0);
#endif
        xfs_dir2_leafn_check(dp, bp);
        /*
         * Look up the hash value in the leaf entries.
         */
        index = xfs_dir2_leaf_search_hash(args, bp);
        /*
         * Do we have a buffer coming in?
         */
        if (state->extravalid) {
                curbp = state->extrablk.bp;
                curdb = state->extrablk.blkno;
        }
        /*
         * Loop over leaf entries with the right hash value.
         */
        for (lep = &leaf->ents[index]; index < be16_to_cpu(leaf->hdr.count) &&
                                be32_to_cpu(lep->hashval) == args->hashval;
                                lep++, index++) {
                /*
                 * Skip stale leaf entries.
                 */
                if (be32_to_cpu(lep->address) == XFS_DIR2_NULL_DATAPTR)
                        continue;
                /*
                 * Pull the data block number from the entry.
                 */
                newdb = xfs_dir2_dataptr_to_db(mp, be32_to_cpu(lep->address));
                /*
                 * Not adding a new entry, so we really want to find
                 * the name given to us.
                 *
                 * If it's a different data block, go get it.
                 */
                if (newdb != curdb) {
                        /*
                         * If we had a block before that we aren't saving
                         * for a CI name, drop it
                         */
                        if (curbp && (args->cmpresult == XFS_CMP_DIFFERENT ||
                                                curdb != state->extrablk.blkno))
                                xfs_da_brelse(tp, curbp);
                        /*
                         * If needing the block that is saved with a CI match,
                         * use it otherwise read in the new data block.
                         */
                        if (args->cmpresult != XFS_CMP_DIFFERENT &&
                                        newdb == state->extrablk.blkno) {
                                ASSERT(state->extravalid);
                                curbp = state->extrablk.bp;
                        } else {
                                error = xfs_da_read_buf(tp, dp,
                                                xfs_dir2_db_to_da(mp, newdb),
                                                -1, &curbp, XFS_DATA_FORK);
                                if (error)
                                        return error;
                        }
                        xfs_dir2_data_check(dp, curbp);
                        curdb = newdb;
                }
                /*
                 * Point to the data entry.
                 */
                dep = (xfs_dir2_data_entry_t *)((char *)curbp->data +
                        xfs_dir2_dataptr_to_off(mp, be32_to_cpu(lep->address)));
                /*
                 * Compare the entry and if it's an exact match, return
                 * EEXIST immediately. If it's the first case-insensitive
                 * match, store the block & inode number and continue looking.
                 */
                cmp = mp->m_dirnameops->compname(args, dep->name, dep->namelen);
                if (cmp != XFS_CMP_DIFFERENT && cmp != args->cmpresult) {
                        /* If there is a CI match block, drop it */
                        if (args->cmpresult != XFS_CMP_DIFFERENT &&
                                                curdb != state->extrablk.blkno)
                                xfs_da_brelse(tp, state->extrablk.bp);
                        args->cmpresult = cmp;
                        args->inumber = be64_to_cpu(dep->inumber);
                        *indexp = index;
                        state->extravalid = 1;
                        state->extrablk.bp = curbp;
                        state->extrablk.blkno = curdb;
                        state->extrablk.index = (int)((char *)dep -
                                                        (char *)curbp->data);
                        state->extrablk.magic = XFS_DIR2_DATA_MAGIC;
                        if (cmp == XFS_CMP_EXACT)
                                return XFS_ERROR(EEXIST);
                }
        }
        ASSERT(index == be16_to_cpu(leaf->hdr.count) ||
                                        (args->op_flags & XFS_DA_OP_OKNOENT));
        if (curbp) {
                if (args->cmpresult == XFS_CMP_DIFFERENT) {
                        /* Giving back last used data block. */
                        state->extravalid = 1;
                        state->extrablk.bp = curbp;
                        state->extrablk.index = -1;
                        state->extrablk.blkno = curdb;
                        state->extrablk.magic = XFS_DIR2_DATA_MAGIC;
                } else {
                        /* If the curbp is not the CI match block, drop it */
                        if (state->extrablk.bp != curbp)
                                xfs_da_brelse(tp, curbp);
                }
        } else {
                state->extravalid = 0;
        }
        *indexp = index;
        return XFS_ERROR(ENOENT);
}

/*
 * Look up a leaf entry in a node-format leaf block.
 * If this is an addname then the extrablk in state is a freespace block,
 * otherwise it's a data block.
 */
int
xfs_dir2_leafn_lookup_int(
        xfs_dabuf_t             *bp,            /* leaf buffer */
        xfs_da_args_t           *args,          /* operation arguments */
        int                     *indexp,        /* out: leaf entry index */
        xfs_da_state_t          *state)         /* state to fill in */
{
        if (args->op_flags & XFS_DA_OP_ADDNAME)
                return xfs_dir2_leafn_lookup_for_addname(bp, args, indexp,
                                                        state);
        return xfs_dir2_leafn_lookup_for_entry(bp, args, indexp, state);
}

/*
 * Move count leaf entries from source to destination leaf.
 * Log entries and headers.  Stale entries are preserved.
 */
static void
xfs_dir2_leafn_moveents(
        xfs_da_args_t   *args,                  /* operation arguments */
        xfs_dabuf_t     *bp_s,                  /* source leaf buffer */
        int             start_s,                /* source leaf index */
        xfs_dabuf_t     *bp_d,                  /* destination leaf buffer */
        int             start_d,                /* destination leaf index */
        int             count)                  /* count of leaves to copy */
{
        xfs_dir2_leaf_t *leaf_d;                /* destination leaf structure */
        xfs_dir2_leaf_t *leaf_s;                /* source leaf structure */
        int             stale;                  /* count stale leaves copied */
        xfs_trans_t     *tp;                    /* transaction pointer */

        trace_xfs_dir2_leafn_moveents(args, start_s, start_d, count);

        /*
         * Silently return if nothing to do.
         */
        if (count == 0) {
                return;
        }
        tp = args->trans;
        leaf_s = bp_s->data;
        leaf_d = bp_d->data;
        /*
         * If the destination index is not the end of the current
         * destination leaf entries, open up a hole in the destination
         * to hold the new entries.
         */
        if (start_d < be16_to_cpu(leaf_d->hdr.count)) {
                memmove(&leaf_d->ents[start_d + count], &leaf_d->ents[start_d],
                        (be16_to_cpu(leaf_d->hdr.count) - start_d) *
                        sizeof(xfs_dir2_leaf_entry_t));
                xfs_dir2_leaf_log_ents(tp, bp_d, start_d + count,
                        count + be16_to_cpu(leaf_d->hdr.count) - 1);
        }
        /*
         * If the source has stale leaves, count the ones in the copy range
         * so we can update the header correctly.
         */
        if (leaf_s->hdr.stale) {
                int     i;                      /* temp leaf index */

                for (i = start_s, stale = 0; i < start_s + count; i++) {
                        if (leaf_s->ents[i].address ==
                            cpu_to_be32(XFS_DIR2_NULL_DATAPTR))
                                stale++;
                }
        } else
                stale = 0;
        /*
         * Copy the leaf entries from source to destination.
         */
        memcpy(&leaf_d->ents[start_d], &leaf_s->ents[start_s],
                count * sizeof(xfs_dir2_leaf_entry_t));
        xfs_dir2_leaf_log_ents(tp, bp_d, start_d, start_d + count - 1);
        /*
         * If there are source entries after the ones we copied,
         * delete the ones we copied by sliding the next ones down.
         */
        if (start_s + count < be16_to_cpu(leaf_s->hdr.count)) {
                memmove(&leaf_s->ents[start_s], &leaf_s->ents[start_s + count],
                        count * sizeof(xfs_dir2_leaf_entry_t));
                xfs_dir2_leaf_log_ents(tp, bp_s, start_s, start_s + count - 1);
        }
        /*
         * Update the headers and log them.
         */
        be16_add_cpu(&leaf_s->hdr.count, -(count));
        be16_add_cpu(&leaf_s->hdr.stale, -(stale));
        be16_add_cpu(&leaf_d->hdr.count, count);
        be16_add_cpu(&leaf_d->hdr.stale, stale);
        xfs_dir2_leaf_log_header(tp, bp_s);
        xfs_dir2_leaf_log_header(tp, bp_d);
        xfs_dir2_leafn_check(args->dp, bp_s);
        xfs_dir2_leafn_check(args->dp, bp_d);
}

/*
 * Determine the sort order of two leaf blocks.
 * Returns 1 if both are valid and leaf2 should be before leaf1, else 0.
 */
int                                             /* sort order */
xfs_dir2_leafn_order(
        xfs_dabuf_t     *leaf1_bp,              /* leaf1 buffer */
        xfs_dabuf_t     *leaf2_bp)              /* leaf2 buffer */
{
        xfs_dir2_leaf_t *leaf1;                 /* leaf1 structure */
        xfs_dir2_leaf_t *leaf2;                 /* leaf2 structure */

        leaf1 = leaf1_bp->data;
        leaf2 = leaf2_bp->data;
        ASSERT(leaf1->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAFN_MAGIC));
        ASSERT(leaf2->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAFN_MAGIC));
        if (be16_to_cpu(leaf1->hdr.count) > 0 &&
            be16_to_cpu(leaf2->hdr.count) > 0 &&
            (be32_to_cpu(leaf2->ents[0].hashval) < be32_to_cpu(leaf1->ents[0].hashval) ||
             be32_to_cpu(leaf2->ents[be16_to_cpu(leaf2->hdr.count) - 1].hashval) <
             be32_to_cpu(leaf1->ents[be16_to_cpu(leaf1->hdr.count) - 1].hashval)))
                return 1;
        return 0;
}

/*
 * Rebalance leaf entries between two leaf blocks.
 * This is actually only called when the second block is new,
 * though the code deals with the general case.
 * A new entry will be inserted in one of the blocks, and that
 * entry is taken into account when balancing.
 */
static void
xfs_dir2_leafn_rebalance(
        xfs_da_state_t          *state,         /* btree cursor */
        xfs_da_state_blk_t      *blk1,          /* first btree block */
        xfs_da_state_blk_t      *blk2)          /* second btree block */
{
        xfs_da_args_t           *args;          /* operation arguments */
        int                     count;          /* count (& direction) leaves */
        int                     isleft;         /* new goes in left leaf */
        xfs_dir2_leaf_t         *leaf1;         /* first leaf structure */
        xfs_dir2_leaf_t         *leaf2;         /* second leaf structure */
        int                     mid;            /* midpoint leaf index */
#ifdef DEBUG
        int                     oldstale;       /* old count of stale leaves */
#endif
        int                     oldsum;         /* old total leaf count */
        int                     swap;           /* swapped leaf blocks */

        args = state->args;
        /*
         * If the block order is wrong, swap the arguments.
         */
        if ((swap = xfs_dir2_leafn_order(blk1->bp, blk2->bp))) {
                xfs_da_state_blk_t      *tmp;   /* temp for block swap */

                tmp = blk1;
                blk1 = blk2;
                blk2 = tmp;
        }
        leaf1 = blk1->bp->data;
        leaf2 = blk2->bp->data;
        oldsum = be16_to_cpu(leaf1->hdr.count) + be16_to_cpu(leaf2->hdr.count);
#ifdef DEBUG
        oldstale = be16_to_cpu(leaf1->hdr.stale) + be16_to_cpu(leaf2->hdr.stale);
#endif
        mid = oldsum >> 1;
        /*
         * If the old leaf count was odd then the new one will be even,
         * so we need to divide the new count evenly.
         */
        if (oldsum & 1) {
                xfs_dahash_t    midhash;        /* middle entry hash value */

                if (mid >= be16_to_cpu(leaf1->hdr.count))
                        midhash = be32_to_cpu(leaf2->ents[mid - be16_to_cpu(leaf1->hdr.count)].hashval);
                else
                        midhash = be32_to_cpu(leaf1->ents[mid].hashval);
                isleft = args->hashval <= midhash;
        }
        /*
         * If the old count is even then the new count is odd, so there's
         * no preferred side for the new entry.
         * Pick the left one.
         */
        else
                isleft = 1;
        /*
         * Calculate moved entry count.  Positive means left-to-right,
         * negative means right-to-left.  Then move the entries.
         */
        count = be16_to_cpu(leaf1->hdr.count) - mid + (isleft == 0);
        if (count > 0)
                xfs_dir2_leafn_moveents(args, blk1->bp,
                        be16_to_cpu(leaf1->hdr.count) - count, blk2->bp, 0, count);
        else if (count < 0)
                xfs_dir2_leafn_moveents(args, blk2->bp, 0, blk1->bp,
                        be16_to_cpu(leaf1->hdr.count), count);
        ASSERT(be16_to_cpu(leaf1->hdr.count) + be16_to_cpu(leaf2->hdr.count) == oldsum);
        ASSERT(be16_to_cpu(leaf1->hdr.stale) + be16_to_cpu(leaf2->hdr.stale) == oldstale);
        /*
         * Mark whether we're inserting into the old or new leaf.
         */
        if (be16_to_cpu(leaf1->hdr.count) < be16_to_cpu(leaf2->hdr.count))
                state->inleaf = swap;
        else if (be16_to_cpu(leaf1->hdr.count) > be16_to_cpu(leaf2->hdr.count))
                state->inleaf = !swap;
        else
                state->inleaf =
                        swap ^ (blk1->index <= be16_to_cpu(leaf1->hdr.count));
        /*
         * Adjust the expected index for insertion.
         */
        if (!state->inleaf)
                blk2->index = blk1->index - be16_to_cpu(leaf1->hdr.count);

        /*
         * Finally sanity check just to make sure we are not returning a
         * negative index
         */
        if(blk2->index < 0) {
                state->inleaf = 1;
                blk2->index = 0;
                xfs_alert(args->dp->i_mount,
        "%s: picked the wrong leaf? reverting original leaf: blk1->index %d\n",
                        __func__, blk1->index);
        }
}

/*
 * Remove an entry from a node directory.
 * This removes the leaf entry and the data entry,
 * and updates the free block if necessary.
 */
static int                                      /* error */
xfs_dir2_leafn_remove(
        xfs_da_args_t           *args,          /* operation arguments */
        xfs_dabuf_t             *bp,            /* leaf buffer */
        int                     index,          /* leaf entry index */
        xfs_da_state_blk_t      *dblk,          /* data block */
        int                     *rval)          /* resulting block needs join */
{
        xfs_dir2_data_hdr_t     *hdr;           /* data block header */
        xfs_dir2_db_t           db;             /* data block number */
        xfs_dabuf_t             *dbp;           /* data block buffer */
        xfs_dir2_data_entry_t   *dep;           /* data block entry */
        xfs_inode_t             *dp;            /* incore directory inode */
        xfs_dir2_leaf_t         *leaf;          /* leaf structure */
        xfs_dir2_leaf_entry_t   *lep;           /* leaf entry */
        int                     longest;        /* longest data free entry */
        int                     off;            /* data block entry offset */
        xfs_mount_t             *mp;            /* filesystem mount point */
        int                     needlog;        /* need to log data header */
        int                     needscan;       /* need to rescan data frees */
        xfs_trans_t             *tp;            /* transaction pointer */

        trace_xfs_dir2_leafn_remove(args, index);

        dp = args->dp;
        tp = args->trans;
        mp = dp->i_mount;
        leaf = bp->data;
        ASSERT(leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAFN_MAGIC));
        /*
         * Point to the entry we're removing.
         */
        lep = &leaf->ents[index];
        /*
         * Extract the data block and offset from the entry.
         */
        db = xfs_dir2_dataptr_to_db(mp, be32_to_cpu(lep->address));
        ASSERT(dblk->blkno == db);
        off = xfs_dir2_dataptr_to_off(mp, be32_to_cpu(lep->address));
        ASSERT(dblk->index == off);
        /*
         * Kill the leaf entry by marking it stale.
         * Log the leaf block changes.
         */
        be16_add_cpu(&leaf->hdr.stale, 1);
        xfs_dir2_leaf_log_header(tp, bp);
        lep->address = cpu_to_be32(XFS_DIR2_NULL_DATAPTR);
        xfs_dir2_leaf_log_ents(tp, bp, index, index);
        /*
         * Make the data entry free.  Keep track of the longest freespace
         * in the data block in case it changes.
         */
        dbp = dblk->bp;
        hdr = dbp->data;
        dep = (xfs_dir2_data_entry_t *)((char *)hdr + off);
        longest = be16_to_cpu(hdr->bestfree[0].length);
        needlog = needscan = 0;
        xfs_dir2_data_make_free(tp, dbp, off,
                xfs_dir2_data_entsize(dep->namelen), &needlog, &needscan);
        /*
         * Rescan the data block freespaces for bestfree.
         * Log the data block header if needed.
         */
        if (needscan)
                xfs_dir2_data_freescan(mp, hdr, &needlog);
        if (needlog)
                xfs_dir2_data_log_header(tp, dbp);
        xfs_dir2_data_check(dp, dbp);
        /*
         * If the longest data block freespace changes, need to update
         * the corresponding freeblock entry.
         */
        if (longest < be16_to_cpu(hdr->bestfree[0].length)) {
                int             error;          /* error return value */
                xfs_dabuf_t     *fbp;           /* freeblock buffer */
                xfs_dir2_db_t   fdb;            /* freeblock block number */
                int             findex;         /* index in freeblock entries */
                xfs_dir2_free_t *free;          /* freeblock structure */
                int             logfree;        /* need to log free entry */

                /*
                 * Convert the data block number to a free block,
                 * read in the free block.
                 */
                fdb = xfs_dir2_db_to_fdb(mp, db);
                if ((error = xfs_da_read_buf(tp, dp, xfs_dir2_db_to_da(mp, fdb),
                                -1, &fbp, XFS_DATA_FORK))) {
                        return error;
                }
                free = fbp->data;
                ASSERT(free->hdr.magic == cpu_to_be32(XFS_DIR2_FREE_MAGIC));
                ASSERT(be32_to_cpu(free->hdr.firstdb) ==
                       xfs_dir2_free_max_bests(mp) *
                       (fdb - XFS_DIR2_FREE_FIRSTDB(mp)));
                /*
                 * Calculate which entry we need to fix.
                 */
                findex = xfs_dir2_db_to_fdindex(mp, db);
                longest = be16_to_cpu(hdr->bestfree[0].length);
                /*
                 * If the data block is now empty we can get rid of it
                 * (usually).
                 */
                if (longest == mp->m_dirblksize - (uint)sizeof(*hdr)) {
                        /*
                         * Try to punch out the data block.
                         */
                        error = xfs_dir2_shrink_inode(args, db, dbp);
                        if (error == 0) {
                                dblk->bp = NULL;
                                hdr = NULL;
                        }
                        /*
                         * We can get ENOSPC if there's no space reservation.
                         * In this case just drop the buffer and some one else
                         * will eventually get rid of the empty block.
                         */
                        else if (error == ENOSPC && args->total == 0)
                                xfs_da_buf_done(dbp);
                        else
                                return error;
                }
                /*
                 * If we got rid of the data block, we can eliminate that entry
                 * in the free block.
                 */
                if (hdr == NULL) {
                        /*
                         * One less used entry in the free table.
                         */
                        be32_add_cpu(&free->hdr.nused, -1);
                        xfs_dir2_free_log_header(tp, fbp);
                        /*
                         * If this was the last entry in the table, we can
                         * trim the table size back.  There might be other
                         * entries at the end referring to non-existent
                         * data blocks, get those too.
                         */
                        if (findex == be32_to_cpu(free->hdr.nvalid) - 1) {
                                int     i;              /* free entry index */

                                for (i = findex - 1;
                                     i >= 0 &&
                                     free->bests[i] == cpu_to_be16(NULLDATAOFF);
                                     i--)
                                        continue;
                                free->hdr.nvalid = cpu_to_be32(i + 1);
                                logfree = 0;
                        }
                        /*
                         * Not the last entry, just punch it out.
                         */
                        else {
                                free->bests[findex] = cpu_to_be16(NULLDATAOFF);
                                logfree = 1;
                        }
                        /*
                         * If there are no useful entries left in the block,
                         * get rid of the block if we can.
                         */
                        if (!free->hdr.nused) {
                                error = xfs_dir2_shrink_inode(args, fdb, fbp);
                                if (error == 0) {
                                        fbp = NULL;
                                        logfree = 0;
                                } else if (error != ENOSPC || args->total != 0)
                                        return error;
                                /*
                                 * It's possible to get ENOSPC if there is no
                                 * space reservation.  In this case some one
                                 * else will eventually get rid of this block.
                                 */
                        }
                }
                /*
                 * Data block is not empty, just set the free entry to
                 * the new value.
                 */
                else {
                        free->bests[findex] = cpu_to_be16(longest);
                        logfree = 1;
                }
                /*
                 * Log the free entry that changed, unless we got rid of it.
                 */
                if (logfree)
                        xfs_dir2_free_log_bests(tp, fbp, findex, findex);
                /*
                 * Drop the buffer if we still have it.
                 */
                if (fbp)
                        xfs_da_buf_done(fbp);
        }
        xfs_dir2_leafn_check(dp, bp);
        /*
         * Return indication of whether this leaf block is empty enough
         * to justify trying to join it with a neighbor.
         */
        *rval =
                ((uint)sizeof(leaf->hdr) +
                 (uint)sizeof(leaf->ents[0]) *
                 (be16_to_cpu(leaf->hdr.count) - be16_to_cpu(leaf->hdr.stale))) <
                mp->m_dir_magicpct;
        return 0;
}

/*
 * Split the leaf entries in the old block into old and new blocks.
 */
int                                             /* error */
xfs_dir2_leafn_split(
        xfs_da_state_t          *state,         /* btree cursor */
        xfs_da_state_blk_t      *oldblk,        /* original block */
        xfs_da_state_blk_t      *newblk)        /* newly created block */
{
        xfs_da_args_t           *args;          /* operation arguments */
        xfs_dablk_t             blkno;          /* new leaf block number */
        int                     error;          /* error return value */
        xfs_mount_t             *mp;            /* filesystem mount point */

        /*
         * Allocate space for a new leaf node.
         */
        args = state->args;
        mp = args->dp->i_mount;
        ASSERT(args != NULL);
        ASSERT(oldblk->magic == XFS_DIR2_LEAFN_MAGIC);
        error = xfs_da_grow_inode(args, &blkno);
        if (error) {
                return error;
        }
        /*
         * Initialize the new leaf block.
         */
        error = xfs_dir2_leaf_init(args, xfs_dir2_da_to_db(mp, blkno),
                &newblk->bp, XFS_DIR2_LEAFN_MAGIC);
        if (error) {
                return error;
        }
        newblk->blkno = blkno;
        newblk->magic = XFS_DIR2_LEAFN_MAGIC;
        /*
         * Rebalance the entries across the two leaves, link the new
         * block into the leaves.
         */
        xfs_dir2_leafn_rebalance(state, oldblk, newblk);
        error = xfs_da_blk_link(state, oldblk, newblk);
        if (error) {
                return error;
        }
        /*
         * Insert the new entry in the correct block.
         */
        if (state->inleaf)
                error = xfs_dir2_leafn_add(oldblk->bp, args, oldblk->index);
        else
                error = xfs_dir2_leafn_add(newblk->bp, args, newblk->index);
        /*
         * Update last hashval in each block since we added the name.
         */
        oldblk->hashval = xfs_dir2_leafn_lasthash(oldblk->bp, NULL);
        newblk->hashval = xfs_dir2_leafn_lasthash(newblk->bp, NULL);
        xfs_dir2_leafn_check(args->dp, oldblk->bp);
        xfs_dir2_leafn_check(args->dp, newblk->bp);
        return error;
}

/*
 * Check a leaf block and its neighbors to see if the block should be
 * collapsed into one or the other neighbor.  Always keep the block
 * with the smaller block number.
 * If the current block is over 50% full, don't try to join it, return 0.
 * If the block is empty, fill in the state structure and return 2.
 * If it can be collapsed, fill in the state structure and return 1.
 * If nothing can be done, return 0.
 */
int                                             /* error */
xfs_dir2_leafn_toosmall(
        xfs_da_state_t          *state,         /* btree cursor */
        int                     *action)        /* resulting action to take */
{
        xfs_da_state_blk_t      *blk;           /* leaf block */
        xfs_dablk_t             blkno;          /* leaf block number */
        xfs_dabuf_t             *bp;            /* leaf buffer */
        int                     bytes;          /* bytes in use */
        int                     count;          /* leaf live entry count */
        int                     error;          /* error return value */
        int                     forward;        /* sibling block direction */
        int                     i;              /* sibling counter */
        xfs_da_blkinfo_t        *info;          /* leaf block header */
        xfs_dir2_leaf_t         *leaf;          /* leaf structure */
        int                     rval;           /* result from path_shift */

        /*
         * Check for the degenerate case of the block being over 50% full.
         * If so, it's not worth even looking to see if we might be able
         * to coalesce with a sibling.
         */
        blk = &state->path.blk[state->path.active - 1];
        info = blk->bp->data;
        ASSERT(info->magic == cpu_to_be16(XFS_DIR2_LEAFN_MAGIC));
        leaf = (xfs_dir2_leaf_t *)info;
        count = be16_to_cpu(leaf->hdr.count) - be16_to_cpu(leaf->hdr.stale);
        bytes = (uint)sizeof(leaf->hdr) + count * (uint)sizeof(leaf->ents[0]);
        if (bytes > (state->blocksize >> 1)) {
                /*
                 * Blk over 50%, don't try to join.
                 */
                *action = 0;
                return 0;
        }
        /*
         * Check for the degenerate case of the block being empty.
         * If the block is empty, we'll simply delete it, no need to
         * coalesce it with a sibling block.  We choose (arbitrarily)
         * to merge with the forward block unless it is NULL.
         */
        if (count == 0) {
                /*
                 * Make altpath point to the block we want to keep and
                 * path point to the block we want to drop (this one).
                 */
                forward = (info->forw != 0);
                memcpy(&state->altpath, &state->path, sizeof(state->path));
                error = xfs_da_path_shift(state, &state->altpath, forward, 0,
                        &rval);
                if (error)
                        return error;
                *action = rval ? 2 : 0;
                return 0;
        }
        /*
         * Examine each sibling block to see if we can coalesce with
         * at least 25% free space to spare.  We need to figure out
         * whether to merge with the forward or the backward block.
         * We prefer coalescing with the lower numbered sibling so as
         * to shrink a directory over time.
         */
        forward = be32_to_cpu(info->forw) < be32_to_cpu(info->back);
        for (i = 0, bp = NULL; i < 2; forward = !forward, i++) {
                blkno = forward ? be32_to_cpu(info->forw) : be32_to_cpu(info->back);
                if (blkno == 0)
                        continue;
                /*
                 * Read the sibling leaf block.
                 */
                if ((error =
                    xfs_da_read_buf(state->args->trans, state->args->dp, blkno,
                            -1, &bp, XFS_DATA_FORK))) {
                        return error;
                }
                ASSERT(bp != NULL);
                /*
                 * Count bytes in the two blocks combined.
                 */
                leaf = (xfs_dir2_leaf_t *)info;
                count = be16_to_cpu(leaf->hdr.count) - be16_to_cpu(leaf->hdr.stale);
                bytes = state->blocksize - (state->blocksize >> 2);
                leaf = bp->data;
                ASSERT(leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAFN_MAGIC));
                count += be16_to_cpu(leaf->hdr.count) - be16_to_cpu(leaf->hdr.stale);
                bytes -= count * (uint)sizeof(leaf->ents[0]);
                /*
                 * Fits with at least 25% to spare.
                 */
                if (bytes >= 0)
                        break;
                xfs_da_brelse(state->args->trans, bp);
        }
        /*
         * Didn't like either block, give up.
         */
        if (i >= 2) {
                *action = 0;
                return 0;
        }
        /*
         * Done with the sibling leaf block here, drop the dabuf
         * so path_shift can get it.
         */
        xfs_da_buf_done(bp);
        /*
         * Make altpath point to the block we want to keep (the lower
         * numbered block) and path point to the block we want to drop.
         */
        memcpy(&state->altpath, &state->path, sizeof(state->path));
        if (blkno < blk->blkno)
                error = xfs_da_path_shift(state, &state->altpath, forward, 0,
                        &rval);
        else
                error = xfs_da_path_shift(state, &state->path, forward, 0,
                        &rval);
        if (error) {
                return error;
        }
        *action = rval ? 0 : 1;
        return 0;
}

/*
 * Move all the leaf entries from drop_blk to save_blk.
 * This is done as part of a join operation.
 */
void
xfs_dir2_leafn_unbalance(
        xfs_da_state_t          *state,         /* cursor */
        xfs_da_state_blk_t      *drop_blk,      /* dead block */
        xfs_da_state_blk_t      *save_blk)      /* surviving block */
{
        xfs_da_args_t           *args;          /* operation arguments */
        xfs_dir2_leaf_t         *drop_leaf;     /* dead leaf structure */
        xfs_dir2_leaf_t         *save_leaf;     /* surviving leaf structure */

        args = state->args;
        ASSERT(drop_blk->magic == XFS_DIR2_LEAFN_MAGIC);
        ASSERT(save_blk->magic == XFS_DIR2_LEAFN_MAGIC);
        drop_leaf = drop_blk->bp->data;
        save_leaf = save_blk->bp->data;
        ASSERT(drop_leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAFN_MAGIC));
        ASSERT(save_leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAFN_MAGIC));
        /*
         * If there are any stale leaf entries, take this opportunity
         * to purge them.
         */
        if (drop_leaf->hdr.stale)
                xfs_dir2_leaf_compact(args, drop_blk->bp);
        if (save_leaf->hdr.stale)
                xfs_dir2_leaf_compact(args, save_blk->bp);
        /*
         * Move the entries from drop to the appropriate end of save.
         */
        drop_blk->hashval = be32_to_cpu(drop_leaf->ents[be16_to_cpu(drop_leaf->hdr.count) - 1].hashval);
        if (xfs_dir2_leafn_order(save_blk->bp, drop_blk->bp))
                xfs_dir2_leafn_moveents(args, drop_blk->bp, 0, save_blk->bp, 0,
                        be16_to_cpu(drop_leaf->hdr.count));
        else
                xfs_dir2_leafn_moveents(args, drop_blk->bp, 0, save_blk->bp,
                        be16_to_cpu(save_leaf->hdr.count), be16_to_cpu(drop_leaf->hdr.count));
        save_blk->hashval = be32_to_cpu(save_leaf->ents[be16_to_cpu(save_leaf->hdr.count) - 1].hashval);
        xfs_dir2_leafn_check(args->dp, save_blk->bp);
}

/*
 * Top-level node form directory addname routine.
 */
int                                             /* error */
xfs_dir2_node_addname(
        xfs_da_args_t           *args)          /* operation arguments */
{
        xfs_da_state_blk_t      *blk;           /* leaf block for insert */
        int                     error;          /* error return value */
        int                     rval;           /* sub-return value */
        xfs_da_state_t          *state;         /* btree cursor */

        trace_xfs_dir2_node_addname(args);

        /*
         * Allocate and initialize the state (btree cursor).
         */
        state = xfs_da_state_alloc();
        state->args = args;
        state->mp = args->dp->i_mount;
        state->blocksize = state->mp->m_dirblksize;
        state->node_ents = state->mp->m_dir_node_ents;
        /*
         * Look up the name.  We're not supposed to find it, but
         * this gives us the insertion point.
         */
        error = xfs_da_node_lookup_int(state, &rval);
        if (error)
                rval = error;
        if (rval != ENOENT) {
                goto done;
        }
        /*
         * Add the data entry to a data block.
         * Extravalid is set to a freeblock found by lookup.
         */
        rval = xfs_dir2_node_addname_int(args,
                state->extravalid ? &state->extrablk : NULL);
        if (rval) {
                goto done;
        }
        blk = &state->path.blk[state->path.active - 1];
        ASSERT(blk->magic == XFS_DIR2_LEAFN_MAGIC);
        /*
         * Add the new leaf entry.
         */
        rval = xfs_dir2_leafn_add(blk->bp, args, blk->index);
        if (rval == 0) {
                /*
                 * It worked, fix the hash values up the btree.
                 */
                if (!(args->op_flags & XFS_DA_OP_JUSTCHECK))
                        xfs_da_fixhashpath(state, &state->path);
        } else {
                /*
                 * It didn't work, we need to split the leaf block.
                 */
                if (args->total == 0) {
                        ASSERT(rval == ENOSPC);
                        goto done;
                }
                /*
                 * Split the leaf block and insert the new entry.
                 */
                rval = xfs_da_split(state);
        }
done:
        xfs_da_state_free(state);
        return rval;
}

/*
 * Add the data entry for a node-format directory name addition.
 * The leaf entry is added in xfs_dir2_leafn_add.
 * We may enter with a freespace block that the lookup found.
 */
static int                                      /* error */
xfs_dir2_node_addname_int(
        xfs_da_args_t           *args,          /* operation arguments */
        xfs_da_state_blk_t      *fblk)          /* optional freespace block */
{
        xfs_dir2_data_hdr_t     *hdr;           /* data block header */
        xfs_dir2_db_t           dbno;           /* data block number */
        xfs_dabuf_t             *dbp;           /* data block buffer */
        xfs_dir2_data_entry_t   *dep;           /* data entry pointer */
        xfs_inode_t             *dp;            /* incore directory inode */
        xfs_dir2_data_unused_t  *dup;           /* data unused entry pointer */
        int                     error;          /* error return value */
        xfs_dir2_db_t           fbno;           /* freespace block number */
        xfs_dabuf_t             *fbp;           /* freespace buffer */
        int                     findex;         /* freespace entry index */
        xfs_dir2_free_t         *free=NULL;     /* freespace block structure */
        xfs_dir2_db_t           ifbno;          /* initial freespace block no */
        xfs_dir2_db_t           lastfbno=0;     /* highest freespace block no */
        int                     length;         /* length of the new entry */
        int                     logfree;        /* need to log free entry */
        xfs_mount_t             *mp;            /* filesystem mount point */
        int                     needlog;        /* need to log data header */
        int                     needscan;       /* need to rescan data frees */
        __be16                  *tagp;          /* data entry tag pointer */
        xfs_trans_t             *tp;            /* transaction pointer */

        dp = args->dp;
        mp = dp->i_mount;
        tp = args->trans;
        length = xfs_dir2_data_entsize(args->namelen);
        /*
         * If we came in with a freespace block that means that lookup
         * found an entry with our hash value.  This is the freespace
         * block for that data entry.
         */
        if (fblk) {
                fbp = fblk->bp;
                /*
                 * Remember initial freespace block number.
                 */
                ifbno = fblk->blkno;
                free = fbp->data;
                ASSERT(free->hdr.magic == cpu_to_be32(XFS_DIR2_FREE_MAGIC));
                findex = fblk->index;
                /*
                 * This means the free entry showed that the data block had
                 * space for our entry, so we remembered it.
                 * Use that data block.
                 */
                if (findex >= 0) {
                        ASSERT(findex < be32_to_cpu(free->hdr.nvalid));
                        ASSERT(be16_to_cpu(free->bests[findex]) != NULLDATAOFF);
                        ASSERT(be16_to_cpu(free->bests[findex]) >= length);
                        dbno = be32_to_cpu(free->hdr.firstdb) + findex;
                }
                /*
                 * The data block looked at didn't have enough room.
                 * We'll start at the beginning of the freespace entries.
                 */
                else {
                        dbno = -1;
                        findex = 0;
                }
        }
        /*
         * Didn't come in with a freespace block, so don't have a data block.
         */
        else {
                ifbno = dbno = -1;
                fbp = NULL;
                findex = 0;
        }
        /*
         * If we don't have a data block yet, we're going to scan the
         * freespace blocks looking for one.  Figure out what the
         * highest freespace block number is.
         */
        if (dbno == -1) {
                xfs_fileoff_t   fo;             /* freespace block number */

                if ((error = xfs_bmap_last_offset(tp, dp, &fo, XFS_DATA_FORK)))
                        return error;
                lastfbno = xfs_dir2_da_to_db(mp, (xfs_dablk_t)fo);
                fbno = ifbno;
        }
        /*
         * While we haven't identified a data block, search the freeblock
         * data for a good data block.  If we find a null freeblock entry,
         * indicating a hole in the data blocks, remember that.
         */
        while (dbno == -1) {
                /*
                 * If we don't have a freeblock in hand, get the next one.
                 */
                if (fbp == NULL) {
                        /*
                         * Happens the first time through unless lookup gave
                         * us a freespace block to start with.
                         */
                        if (++fbno == 0)
                                fbno = XFS_DIR2_FREE_FIRSTDB(mp);
                        /*
                         * If it's ifbno we already looked at it.
                         */
                        if (fbno == ifbno)
                                fbno++;
                        /*
                         * If it's off the end we're done.
                         */
                        if (fbno >= lastfbno)
                                break;
                        /*
                         * Read the block.  There can be holes in the
                         * freespace blocks, so this might not succeed.
                         * This should be really rare, so there's no reason
                         * to avoid it.
                         */
                        if ((error = xfs_da_read_buf(tp, dp,
                                        xfs_dir2_db_to_da(mp, fbno), -2, &fbp,
                                        XFS_DATA_FORK))) {
                                return error;
                        }
                        if (unlikely(fbp == NULL)) {
                                continue;
                        }
                        free = fbp->data;
                        ASSERT(free->hdr.magic == cpu_to_be32(XFS_DIR2_FREE_MAGIC));
                        findex = 0;
                }
                /*
                 * Look at the current free entry.  Is it good enough?
                 */
                if (be16_to_cpu(free->bests[findex]) != NULLDATAOFF &&
                    be16_to_cpu(free->bests[findex]) >= length)
                        dbno = be32_to_cpu(free->hdr.firstdb) + findex;
                else {
                        /*
                         * Are we done with the freeblock?
                         */
                        if (++findex == be32_to_cpu(free->hdr.nvalid)) {
                                /*
                                 * Drop the block.
                                 */
                                xfs_da_brelse(tp, fbp);
                                fbp = NULL;
                                if (fblk && fblk->bp)
                                        fblk->bp = NULL;
                        }
                }
        }
        /*
         * If we don't have a data block, we need to allocate one and make
         * the freespace entries refer to it.
         */
        if (unlikely(dbno == -1)) {
                /*
                 * Not allowed to allocate, return failure.
                 */
                if ((args->op_flags & XFS_DA_OP_JUSTCHECK) ||
                                                        args->total == 0) {
                        /*
                         * Drop the freespace buffer unless it came from our
                         * caller.
                         */
                        if ((fblk == NULL || fblk->bp == NULL) && fbp != NULL)
                                xfs_da_buf_done(fbp);
                        return XFS_ERROR(ENOSPC);
                }
                /*
                 * Allocate and initialize the new data block.
                 */
                if (unlikely((error = xfs_dir2_grow_inode(args,
                                                         XFS_DIR2_DATA_SPACE,
                                                         &dbno)) ||
                    (error = xfs_dir2_data_init(args, dbno, &dbp)))) {
                        /*
                         * Drop the freespace buffer unless it came from our
                         * caller.
                         */
                        if ((fblk == NULL || fblk->bp == NULL) && fbp != NULL)
                                xfs_da_buf_done(fbp);
                        return error;
                }
                /*
                 * If (somehow) we have a freespace block, get rid of it.
                 */
                if (fbp)
                        xfs_da_brelse(tp, fbp);
                if (fblk && fblk->bp)
                        fblk->bp = NULL;

                /*
                 * Get the freespace block corresponding to the data block
                 * that was just allocated.
                 */
                fbno = xfs_dir2_db_to_fdb(mp, dbno);
                if (unlikely(error = xfs_da_read_buf(tp, dp,
                                xfs_dir2_db_to_da(mp, fbno), -2, &fbp,
                                XFS_DATA_FORK))) {
                        xfs_da_buf_done(dbp);
                        return error;
                }
                /*
                 * If there wasn't a freespace block, the read will
                 * return a NULL fbp.  Allocate and initialize a new one.
                 */
                if( fbp == NULL ) {
                        if ((error = xfs_dir2_grow_inode(args, XFS_DIR2_FREE_SPACE,
                                                        &fbno))) {
                                return error;
                        }

                        if (unlikely(xfs_dir2_db_to_fdb(mp, dbno) != fbno)) {
                                xfs_alert(mp,
                        "%s: dir ino %llu needed freesp block %lld for\n"
                        "  data block %lld, got %lld ifbno %llu lastfbno %d",
                                        __func__, (unsigned long long)dp->i_ino,
                                        (long long)xfs_dir2_db_to_fdb(mp, dbno),
                                        (long long)dbno, (long long)fbno,
                                        (unsigned long long)ifbno, lastfbno);
                                if (fblk) {
                                        xfs_alert(mp,
                                " fblk 0x%p blkno %llu index %d magic 0x%x",
                                                fblk,
                                                (unsigned long long)fblk->blkno,
                                                fblk->index,
                                                fblk->magic);
                                } else {
                                        xfs_alert(mp, " ... fblk is NULL");
                                }
                                XFS_ERROR_REPORT("xfs_dir2_node_addname_int",
                                                 XFS_ERRLEVEL_LOW, mp);
                                return XFS_ERROR(EFSCORRUPTED);
                        }

                        /*
                         * Get a buffer for the new block.
                         */
                        if ((error = xfs_da_get_buf(tp, dp,
                                                   xfs_dir2_db_to_da(mp, fbno),
                                                   -1, &fbp, XFS_DATA_FORK))) {
                                return error;
                        }
                        ASSERT(fbp != NULL);

                        /*
                         * Initialize the new block to be empty, and remember
                         * its first slot as our empty slot.
                         */
                        free = fbp->data;
                        free->hdr.magic = cpu_to_be32(XFS_DIR2_FREE_MAGIC);
                        free->hdr.firstdb = cpu_to_be32(
                                (fbno - XFS_DIR2_FREE_FIRSTDB(mp)) *
                                xfs_dir2_free_max_bests(mp));
                        free->hdr.nvalid = 0;
                        free->hdr.nused = 0;
                } else {
                        free = fbp->data;
                        ASSERT(free->hdr.magic == cpu_to_be32(XFS_DIR2_FREE_MAGIC));
                }

                /*
                 * Set the freespace block index from the data block number.
                 */
                findex = xfs_dir2_db_to_fdindex(mp, dbno);
                /*
                 * If it's after the end of the current entries in the
                 * freespace block, extend that table.
                 */
                if (findex >= be32_to_cpu(free->hdr.nvalid)) {
                        ASSERT(findex < xfs_dir2_free_max_bests(mp));
                        free->hdr.nvalid = cpu_to_be32(findex + 1);
                        /*
                         * Tag new entry so nused will go up.
                         */
                        free->bests[findex] = cpu_to_be16(NULLDATAOFF);
                }
                /*
                 * If this entry was for an empty data block
                 * (this should always be true) then update the header.
                 */
                if (free->bests[findex] == cpu_to_be16(NULLDATAOFF)) {
                        be32_add_cpu(&free->hdr.nused, 1);
                        xfs_dir2_free_log_header(tp, fbp);
                }
                /*
                 * Update the real value in the table.
                 * We haven't allocated the data entry yet so this will
                 * change again.
                 */
                hdr = dbp->data;
                free->bests[findex] = hdr->bestfree[0].length;
                logfree = 1;
        }
        /*
         * We had a data block so we don't have to make a new one.
         */
        else {
                /*
                 * If just checking, we succeeded.
                 */
                if (args->op_flags & XFS_DA_OP_JUSTCHECK) {
                        if ((fblk == NULL || fblk->bp == NULL) && fbp != NULL)
                                xfs_da_buf_done(fbp);
                        return 0;
                }
                /*
                 * Read the data block in.
                 */
                if (unlikely(
                    error = xfs_da_read_buf(tp, dp, xfs_dir2_db_to_da(mp, dbno),
                                -1, &dbp, XFS_DATA_FORK))) {
                        if ((fblk == NULL || fblk->bp == NULL) && fbp != NULL)
                                xfs_da_buf_done(fbp);
                        return error;
                }
                hdr = dbp->data;
                logfree = 0;
        }
        ASSERT(be16_to_cpu(hdr->bestfree[0].length) >= length);
        /*
         * Point to the existing unused space.
         */
        dup = (xfs_dir2_data_unused_t *)
              ((char *)hdr + be16_to_cpu(hdr->bestfree[0].offset));
        needscan = needlog = 0;
        /*
         * Mark the first part of the unused space, inuse for us.
         */
        xfs_dir2_data_use_free(tp, dbp, dup,
                (xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr), length,
                &needlog, &needscan);
        /*
         * Fill in the new entry and log it.
         */
        dep = (xfs_dir2_data_entry_t *)dup;
        dep->inumber = cpu_to_be64(args->inumber);
        dep->namelen = args->namelen;
        memcpy(dep->name, args->name, dep->namelen);
        tagp = xfs_dir2_data_entry_tag_p(dep);
        *tagp = cpu_to_be16((char *)dep - (char *)hdr);
        xfs_dir2_data_log_entry(tp, dbp, dep);
        /*
         * Rescan the block for bestfree if needed.
         */
        if (needscan)
                xfs_dir2_data_freescan(mp, hdr, &needlog);
        /*
         * Log the data block header if needed.
         */
        if (needlog)
                xfs_dir2_data_log_header(tp, dbp);
        /*
         * If the freespace entry is now wrong, update it.
         */
        if (be16_to_cpu(free->bests[findex]) != be16_to_cpu(hdr->bestfree[0].length)) {
                free->bests[findex] = hdr->bestfree[0].length;
                logfree = 1;
        }
        /*
         * Log the freespace entry if needed.
         */
        if (logfree)
                xfs_dir2_free_log_bests(tp, fbp, findex, findex);
        /*
         * If the caller didn't hand us the freespace block, drop it.
         */
        if ((fblk == NULL || fblk->bp == NULL) && fbp != NULL)
                xfs_da_buf_done(fbp);
        /*
         * Return the data block and offset in args, then drop the data block.
         */
        args->blkno = (xfs_dablk_t)dbno;
        args->index = be16_to_cpu(*tagp);
        xfs_da_buf_done(dbp);
        return 0;
}

/*
 * Lookup an entry in a node-format directory.
 * All the real work happens in xfs_da_node_lookup_int.
 * The only real output is the inode number of the entry.
 */
int                                             /* error */
xfs_dir2_node_lookup(
        xfs_da_args_t   *args)                  /* operation arguments */
{
        int             error;                  /* error return value */
        int             i;                      /* btree level */
        int             rval;                   /* operation return value */
        xfs_da_state_t  *state;                 /* btree cursor */

        trace_xfs_dir2_node_lookup(args);

        /*
         * Allocate and initialize the btree cursor.
         */
        state = xfs_da_state_alloc();
        state->args = args;
        state->mp = args->dp->i_mount;
        state->blocksize = state->mp->m_dirblksize;
        state->node_ents = state->mp->m_dir_node_ents;
        /*
         * Fill in the path to the entry in the cursor.
         */
        error = xfs_da_node_lookup_int(state, &rval);
        if (error)
                rval = error;
        else if (rval == ENOENT && args->cmpresult == XFS_CMP_CASE) {
                /* If a CI match, dup the actual name and return EEXIST */
                xfs_dir2_data_entry_t   *dep;

                dep = (xfs_dir2_data_entry_t *)((char *)state->extrablk.bp->
                                                data + state->extrablk.index);
                rval = xfs_dir_cilookup_result(args, dep->name, dep->namelen);
        }
        /*
         * Release the btree blocks and leaf block.
         */
        for (i = 0; i < state->path.active; i++) {
                xfs_da_brelse(args->trans, state->path.blk[i].bp);
                state->path.blk[i].bp = NULL;
        }
        /*
         * Release the data block if we have it.
         */
        if (state->extravalid && state->extrablk.bp) {
                xfs_da_brelse(args->trans, state->extrablk.bp);
                state->extrablk.bp = NULL;
        }
        xfs_da_state_free(state);
        return rval;
}

/*
 * Remove an entry from a node-format directory.
 */
int                                             /* error */
xfs_dir2_node_removename(
        xfs_da_args_t           *args)          /* operation arguments */
{
        xfs_da_state_blk_t      *blk;           /* leaf block */
        int                     error;          /* error return value */
        int                     rval;           /* operation return value */
        xfs_da_state_t          *state;         /* btree cursor */

        trace_xfs_dir2_node_removename(args);

        /*
         * Allocate and initialize the btree cursor.
         */
        state = xfs_da_state_alloc();
        state->args = args;
        state->mp = args->dp->i_mount;
        state->blocksize = state->mp->m_dirblksize;
        state->node_ents = state->mp->m_dir_node_ents;
        /*
         * Look up the entry we're deleting, set up the cursor.
         */
        error = xfs_da_node_lookup_int(state, &rval);
        if (error)
                rval = error;
        /*
         * Didn't find it, upper layer screwed up.
         */
        if (rval != EEXIST) {
                xfs_da_state_free(state);
                return rval;
        }
        blk = &state->path.blk[state->path.active - 1];
        ASSERT(blk->magic == XFS_DIR2_LEAFN_MAGIC);
        ASSERT(state->extravalid);
        /*
         * Remove the leaf and data entries.
         * Extrablk refers to the data block.
         */
        error = xfs_dir2_leafn_remove(args, blk->bp, blk->index,
                &state->extrablk, &rval);
        if (error)
                return error;
        /*
         * Fix the hash values up the btree.
         */
        xfs_da_fixhashpath(state, &state->path);
        /*
         * If we need to join leaf blocks, do it.
         */
        if (rval && state->path.active > 1)
                error = xfs_da_join(state);
        /*
         * If no errors so far, try conversion to leaf format.
         */
        if (!error)
                error = xfs_dir2_node_to_leaf(state);
        xfs_da_state_free(state);
        return error;
}

/*
 * Replace an entry's inode number in a node-format directory.
 */
int                                             /* error */
xfs_dir2_node_replace(
        xfs_da_args_t           *args)          /* operation arguments */
{
        xfs_da_state_blk_t      *blk;           /* leaf block */
        xfs_dir2_data_hdr_t     *hdr;           /* data block header */
        xfs_dir2_data_entry_t   *dep;           /* data entry changed */
        int                     error;          /* error return value */
        int                     i;              /* btree level */
        xfs_ino_t               inum;           /* new inode number */
        xfs_dir2_leaf_t         *leaf;          /* leaf structure */
        xfs_dir2_leaf_entry_t   *lep;           /* leaf entry being changed */
        int                     rval;           /* internal return value */
        xfs_da_state_t          *state;         /* btree cursor */

        trace_xfs_dir2_node_replace(args);

        /*
         * Allocate and initialize the btree cursor.
         */
        state = xfs_da_state_alloc();
        state->args = args;
        state->mp = args->dp->i_mount;
        state->blocksize = state->mp->m_dirblksize;
        state->node_ents = state->mp->m_dir_node_ents;
        inum = args->inumber;
        /*
         * Lookup the entry to change in the btree.
         */
        error = xfs_da_node_lookup_int(state, &rval);
        if (error) {
                rval = error;
        }
        /*
         * It should be found, since the vnodeops layer has looked it up
         * and locked it.  But paranoia is good.
         */
        if (rval == EEXIST) {
                /*
                 * Find the leaf entry.
                 */
                blk = &state->path.blk[state->path.active - 1];
                ASSERT(blk->magic == XFS_DIR2_LEAFN_MAGIC);
                leaf = blk->bp->data;
                lep = &leaf->ents[blk->index];
                ASSERT(state->extravalid);
                /*
                 * Point to the data entry.
                 */
                hdr = state->extrablk.bp->data;
                ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC));
                dep = (xfs_dir2_data_entry_t *)
                      ((char *)hdr +
                       xfs_dir2_dataptr_to_off(state->mp, be32_to_cpu(lep->address)));
                ASSERT(inum != be64_to_cpu(dep->inumber));
                /*
                 * Fill in the new inode number and log the entry.
                 */
                dep->inumber = cpu_to_be64(inum);
                xfs_dir2_data_log_entry(args->trans, state->extrablk.bp, dep);
                rval = 0;
        }
        /*
         * Didn't find it, and we're holding a data block.  Drop it.
         */
        else if (state->extravalid) {
                xfs_da_brelse(args->trans, state->extrablk.bp);
                state->extrablk.bp = NULL;
        }
        /*
         * Release all the buffers in the cursor.
         */
        for (i = 0; i < state->path.active; i++) {
                xfs_da_brelse(args->trans, state->path.blk[i].bp);
                state->path.blk[i].bp = NULL;
        }
        xfs_da_state_free(state);
        return rval;
}

/*
 * Trim off a trailing empty freespace block.
 * Return (in rvalp) 1 if we did it, 0 if not.
 */
int                                             /* error */
xfs_dir2_node_trim_free(
        xfs_da_args_t           *args,          /* operation arguments */
        xfs_fileoff_t           fo,             /* free block number */
        int                     *rvalp)         /* out: did something */
{
        xfs_dabuf_t             *bp;            /* freespace buffer */
        xfs_inode_t             *dp;            /* incore directory inode */
        int                     error;          /* error return code */
        xfs_dir2_free_t         *free;          /* freespace structure */
        xfs_mount_t             *mp;            /* filesystem mount point */
        xfs_trans_t             *tp;            /* transaction pointer */

        dp = args->dp;
        mp = dp->i_mount;
        tp = args->trans;
        /*
         * Read the freespace block.
         */
        if (unlikely(error = xfs_da_read_buf(tp, dp, (xfs_dablk_t)fo, -2, &bp,
                        XFS_DATA_FORK))) {
                return error;
        }

        /*
         * There can be holes in freespace.  If fo is a hole, there's
         * nothing to do.
         */
        if (bp == NULL) {
                return 0;
        }
        free = bp->data;
        ASSERT(free->hdr.magic == cpu_to_be32(XFS_DIR2_FREE_MAGIC));
        /*
         * If there are used entries, there's nothing to do.
         */
        if (be32_to_cpu(free->hdr.nused) > 0) {
                xfs_da_brelse(tp, bp);
                *rvalp = 0;
                return 0;
        }
        /*
         * Blow the block away.
         */
        if ((error =
            xfs_dir2_shrink_inode(args, xfs_dir2_da_to_db(mp, (xfs_dablk_t)fo),
                    bp))) {
                /*
                 * Can't fail with ENOSPC since that only happens with no
                 * space reservation, when breaking up an extent into two
                 * pieces.  This is the last block of an extent.
                 */
                ASSERT(error != ENOSPC);
                xfs_da_brelse(tp, bp);
                return error;
        }
        /*
         * Return that we succeeded.
         */
        *rvalp = 1;
        return 0;
}