xfs_dir2_leaf.c

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/*
 * Copyright (c) 2000-2003,2005 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_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"

/*
 * Local function declarations.
 */
#ifdef DEBUG
static void xfs_dir2_leaf_check(struct xfs_inode *dp, struct xfs_buf *bp);
#else
#define xfs_dir2_leaf_check(dp, bp)
#endif
static int xfs_dir2_leaf_lookup_int(xfs_da_args_t *args, struct xfs_buf **lbpp,
                    int *indexp, struct xfs_buf **dbpp);
static void xfs_dir2_leaf_log_bests(struct xfs_trans *tp, struct xfs_buf *bp,
                    int first, int last);
static void xfs_dir2_leaf_log_tail(struct xfs_trans *tp, struct xfs_buf *bp);


/*
 * Convert a block form directory to a leaf form directory.
 */
int                     /* error */
xfs_dir2_block_to_leaf(
    xfs_da_args_t       *args,      /* operation arguments */
    struct xfs_buf      *dbp)       /* input block's buffer */
{
    __be16          *bestsp;    /* leaf's bestsp entries */
    xfs_dablk_t     blkno;      /* leaf block's bno */
    xfs_dir2_data_hdr_t *hdr;       /* block header */
    xfs_dir2_leaf_entry_t   *blp;       /* block's leaf entries */
    xfs_dir2_block_tail_t   *btp;       /* block's tail */
    xfs_inode_t     *dp;        /* incore directory inode */
    int         error;      /* error return code */
    struct xfs_buf      *lbp;       /* leaf block's buffer */
    xfs_dir2_db_t       ldb;        /* leaf block's bno */
    xfs_dir2_leaf_t     *leaf;      /* leaf structure */
    xfs_dir2_leaf_tail_t    *ltp;       /* leaf's tail */
    xfs_mount_t     *mp;        /* filesystem mount point */
    int         needlog;    /* need to log block header */
    int         needscan;   /* need to rescan bestfree */
    xfs_trans_t     *tp;        /* transaction pointer */

    trace_xfs_dir2_block_to_leaf(args);

    dp = args->dp;
    mp = dp->i_mount;
    tp = args->trans;
    /*
     * Add the leaf block to the inode.
     * This interface will only put blocks in the leaf/node range.
     * Since that's empty now, we'll get the root (block 0 in range).
     */
    if ((error = xfs_da_grow_inode(args, &blkno))) {
        return error;
    }
    ldb = xfs_dir2_da_to_db(mp, blkno);
    ASSERT(ldb == XFS_DIR2_LEAF_FIRSTDB(mp));
    /*
     * Initialize the leaf block, get a buffer for it.
     */
    if ((error = xfs_dir2_leaf_init(args, ldb, &lbp, XFS_DIR2_LEAF1_MAGIC))) {
        return error;
    }
    ASSERT(lbp != NULL);
    leaf = lbp->b_addr;
    hdr = dbp->b_addr;
    xfs_dir2_data_check(dp, dbp);
    btp = xfs_dir2_block_tail_p(mp, hdr);
    blp = xfs_dir2_block_leaf_p(btp);
    /*
     * Set the counts in the leaf header.
     */
    leaf->hdr.count = cpu_to_be16(be32_to_cpu(btp->count));
    leaf->hdr.stale = cpu_to_be16(be32_to_cpu(btp->stale));
    /*
     * Could compact these but I think we always do the conversion
     * after squeezing out stale entries.
     */
    memcpy(leaf->ents, blp, be32_to_cpu(btp->count) * sizeof(xfs_dir2_leaf_entry_t));
    xfs_dir2_leaf_log_ents(tp, lbp, 0, be16_to_cpu(leaf->hdr.count) - 1);
    needscan = 0;
    needlog = 1;
    /*
     * Make the space formerly occupied by the leaf entries and block
     * tail be free.
     */
    xfs_dir2_data_make_free(tp, dbp,
        (xfs_dir2_data_aoff_t)((char *)blp - (char *)hdr),
        (xfs_dir2_data_aoff_t)((char *)hdr + mp->m_dirblksize -
                       (char *)blp),
        &needlog, &needscan);
    /*
     * Fix up the block header, make it a data block.
     */
    hdr->magic = cpu_to_be32(XFS_DIR2_DATA_MAGIC);
    if (needscan)
        xfs_dir2_data_freescan(mp, hdr, &needlog);
    /*
     * Set up leaf tail and bests table.
     */
    ltp = xfs_dir2_leaf_tail_p(mp, leaf);
    ltp->bestcount = cpu_to_be32(1);
    bestsp = xfs_dir2_leaf_bests_p(ltp);
    bestsp[0] =  hdr->bestfree[0].length;
    /*
     * Log the data header and leaf bests table.
     */
    if (needlog)
        xfs_dir2_data_log_header(tp, dbp);
    xfs_dir2_leaf_check(dp, lbp);
    xfs_dir2_data_check(dp, dbp);
    xfs_dir2_leaf_log_bests(tp, lbp, 0, 0);
    return 0;
}

STATIC void
xfs_dir2_leaf_find_stale(
    struct xfs_dir2_leaf    *leaf,
    int         index,
    int         *lowstale,
    int         *highstale)
{
    /*
     * Find the first stale entry before our index, if any.
     */
    for (*lowstale = index - 1; *lowstale >= 0; --*lowstale) {
        if (leaf->ents[*lowstale].address ==
            cpu_to_be32(XFS_DIR2_NULL_DATAPTR))
            break;
    }

    /*
     * Find the first stale entry at or after our index, if any.
     * Stop if the result would require moving more entries than using
     * lowstale.
     */
    for (*highstale = index;
         *highstale < be16_to_cpu(leaf->hdr.count);
         ++*highstale) {
        if (leaf->ents[*highstale].address ==
            cpu_to_be32(XFS_DIR2_NULL_DATAPTR))
            break;
        if (*lowstale >= 0 && index - *lowstale <= *highstale - index)
            break;
    }
}

struct xfs_dir2_leaf_entry *
xfs_dir2_leaf_find_entry(
    xfs_dir2_leaf_t     *leaf,      /* leaf structure */
    int         index,      /* leaf table position */
    int         compact,    /* need to compact leaves */
    int         lowstale,   /* index of prev stale leaf */
    int         highstale,  /* index of next stale leaf */
    int         *lfloglow,  /* low leaf logging index */
    int         *lfloghigh) /* high leaf logging index */
{
    if (!leaf->hdr.stale) {
        xfs_dir2_leaf_entry_t   *lep;   /* leaf entry table pointer */

        /*
         * Now we need to make room to insert the leaf entry.
         *
         * If there are no stale entries, just insert a hole at index.
         */
        lep = &leaf->ents[index];
        if (index < be16_to_cpu(leaf->hdr.count))
            memmove(lep + 1, lep,
                (be16_to_cpu(leaf->hdr.count) - index) *
                 sizeof(*lep));

        /*
         * Record low and high logging indices for the leaf.
         */
        *lfloglow = index;
        *lfloghigh = be16_to_cpu(leaf->hdr.count);
        be16_add_cpu(&leaf->hdr.count, 1);
        return lep;
    }

    /*
     * There are stale entries.
     *
     * We will use one of them for the new entry.  It's probably not at
     * the right location, so we'll have to shift some up or down first.
     *
     * If we didn't compact before, we need to find the nearest stale
     * entries before and after our insertion point.
     */
    if (compact == 0)
        xfs_dir2_leaf_find_stale(leaf, index, &lowstale, &highstale);

    /*
     * If the low one is better, use it.
     */
    if (lowstale >= 0 &&
        (highstale == be16_to_cpu(leaf->hdr.count) ||
         index - lowstale - 1 < highstale - index)) {
        ASSERT(index - lowstale - 1 >= 0);
        ASSERT(leaf->ents[lowstale].address ==
               cpu_to_be32(XFS_DIR2_NULL_DATAPTR));

        /*
         * Copy entries up to cover the stale entry and make room
         * for the new entry.
         */
        if (index - lowstale - 1 > 0) {
            memmove(&leaf->ents[lowstale],
                &leaf->ents[lowstale + 1],
                (index - lowstale - 1) *
                sizeof(xfs_dir2_leaf_entry_t));
        }
        *lfloglow = MIN(lowstale, *lfloglow);
        *lfloghigh = MAX(index - 1, *lfloghigh);
        be16_add_cpu(&leaf->hdr.stale, -1);
        return &leaf->ents[index - 1];
    }

    /*
     * The high one is better, so use that one.
     */
    ASSERT(highstale - index >= 0);
    ASSERT(leaf->ents[highstale].address ==
           cpu_to_be32(XFS_DIR2_NULL_DATAPTR));

    /*
     * Copy entries down to cover the stale entry and make room for the
     * new entry.
     */
    if (highstale - index > 0) {
        memmove(&leaf->ents[index + 1],
            &leaf->ents[index],
            (highstale - index) * sizeof(xfs_dir2_leaf_entry_t));
    }
    *lfloglow = MIN(index, *lfloglow);
    *lfloghigh = MAX(highstale, *lfloghigh);
    be16_add_cpu(&leaf->hdr.stale, -1);
    return &leaf->ents[index];
}

/*
 * Add an entry to a leaf form directory.
 */
int                     /* error */
xfs_dir2_leaf_addname(
    xfs_da_args_t       *args)      /* operation arguments */
{
    __be16          *bestsp;    /* freespace table in leaf */
    int         compact;    /* need to compact leaves */
    xfs_dir2_data_hdr_t *hdr;       /* data block header */
    struct xfs_buf      *dbp;       /* data block buffer */
    xfs_dir2_data_entry_t   *dep;       /* data block entry */
    xfs_inode_t     *dp;        /* incore directory inode */
    xfs_dir2_data_unused_t  *dup;       /* data unused entry */
    int         error;      /* error return value */
    int         grown;      /* allocated new data block */
    int         highstale;  /* index of next stale leaf */
    int         i;      /* temporary, index */
    int         index;      /* leaf table position */
    struct xfs_buf      *lbp;       /* leaf's buffer */
    xfs_dir2_leaf_t     *leaf;      /* leaf structure */
    int         length;     /* length of new entry */
    xfs_dir2_leaf_entry_t   *lep;       /* leaf entry table pointer */
    int         lfloglow;   /* low leaf logging index */
    int         lfloghigh;  /* high leaf logging index */
    int         lowstale;   /* index of prev stale leaf */
    xfs_dir2_leaf_tail_t    *ltp;       /* leaf tail pointer */
    xfs_mount_t     *mp;        /* filesystem mount point */
    int         needbytes;  /* leaf block bytes needed */
    int         needlog;    /* need to log data header */
    int         needscan;   /* need to rescan data free */
    __be16          *tagp;      /* end of data entry */
    xfs_trans_t     *tp;        /* transaction pointer */
    xfs_dir2_db_t       use_block;  /* data block number */

    trace_xfs_dir2_leaf_addname(args);

    dp = args->dp;
    tp = args->trans;
    mp = dp->i_mount;
    /*
     * Read the leaf block.
     */
    error = xfs_da_read_buf(tp, dp, mp->m_dirleafblk, -1, &lbp,
        XFS_DATA_FORK);
    if (error) {
        return error;
    }
    ASSERT(lbp != NULL);
    /*
     * Look up the entry by hash value and name.
     * We know it's not there, our caller has already done a lookup.
     * So the index is of the entry to insert in front of.
     * But if there are dup hash values the index is of the first of those.
     */
    index = xfs_dir2_leaf_search_hash(args, lbp);
    leaf = lbp->b_addr;
    ltp = xfs_dir2_leaf_tail_p(mp, leaf);
    bestsp = xfs_dir2_leaf_bests_p(ltp);
    length = xfs_dir2_data_entsize(args->namelen);
    /*
     * See if there are any entries with the same hash value
     * and space in their block for the new entry.
     * This is good because it puts multiple same-hash value entries
     * in a data block, improving the lookup of those entries.
     */
    for (use_block = -1, lep = &leaf->ents[index];
         index < be16_to_cpu(leaf->hdr.count) && be32_to_cpu(lep->hashval) == args->hashval;
         index++, lep++) {
        if (be32_to_cpu(lep->address) == XFS_DIR2_NULL_DATAPTR)
            continue;
        i = xfs_dir2_dataptr_to_db(mp, be32_to_cpu(lep->address));
        ASSERT(i < be32_to_cpu(ltp->bestcount));
        ASSERT(bestsp[i] != cpu_to_be16(NULLDATAOFF));
        if (be16_to_cpu(bestsp[i]) >= length) {
            use_block = i;
            break;
        }
    }
    /*
     * Didn't find a block yet, linear search all the data blocks.
     */
    if (use_block == -1) {
        for (i = 0; i < be32_to_cpu(ltp->bestcount); i++) {
            /*
             * Remember a block we see that's missing.
             */
            if (bestsp[i] == cpu_to_be16(NULLDATAOFF) &&
                use_block == -1)
                use_block = i;
            else if (be16_to_cpu(bestsp[i]) >= length) {
                use_block = i;
                break;
            }
        }
    }
    /*
     * How many bytes do we need in the leaf block?
     */
    needbytes = 0;
    if (!leaf->hdr.stale)
        needbytes += sizeof(xfs_dir2_leaf_entry_t);
    if (use_block == -1)
        needbytes += sizeof(xfs_dir2_data_off_t);

    /*
     * Now kill use_block if it refers to a missing block, so we
     * can use it as an indication of allocation needed.
     */
    if (use_block != -1 && bestsp[use_block] == cpu_to_be16(NULLDATAOFF))
        use_block = -1;
    /*
     * If we don't have enough free bytes but we can make enough
     * by compacting out stale entries, we'll do that.
     */
    if ((char *)bestsp - (char *)&leaf->ents[be16_to_cpu(leaf->hdr.count)] <
                needbytes && be16_to_cpu(leaf->hdr.stale) > 1) {
        compact = 1;
    }
    /*
     * Otherwise if we don't have enough free bytes we need to
     * convert to node form.
     */
    else if ((char *)bestsp - (char *)&leaf->ents[be16_to_cpu(
                        leaf->hdr.count)] < needbytes) {
        /*
         * Just checking or no space reservation, give up.
         */
        if ((args->op_flags & XFS_DA_OP_JUSTCHECK) ||
                            args->total == 0) {
            xfs_trans_brelse(tp, lbp);
            return XFS_ERROR(ENOSPC);
        }
        /*
         * Convert to node form.
         */
        error = xfs_dir2_leaf_to_node(args, lbp);
        if (error)
            return error;
        /*
         * Then add the new entry.
         */
        return xfs_dir2_node_addname(args);
    }
    /*
     * Otherwise it will fit without compaction.
     */
    else
        compact = 0;
    /*
     * If just checking, then it will fit unless we needed to allocate
     * a new data block.
     */
    if (args->op_flags & XFS_DA_OP_JUSTCHECK) {
        xfs_trans_brelse(tp, lbp);
        return use_block == -1 ? XFS_ERROR(ENOSPC) : 0;
    }
    /*
     * If no allocations are allowed, return now before we've
     * changed anything.
     */
    if (args->total == 0 && use_block == -1) {
        xfs_trans_brelse(tp, lbp);
        return XFS_ERROR(ENOSPC);
    }
    /*
     * Need to compact the leaf entries, removing stale ones.
     * Leave one stale entry behind - the one closest to our
     * insertion index - and we'll shift that one to our insertion
     * point later.
     */
    if (compact) {
        xfs_dir2_leaf_compact_x1(lbp, &index, &lowstale, &highstale,
            &lfloglow, &lfloghigh);
    }
    /*
     * There are stale entries, so we'll need log-low and log-high
     * impossibly bad values later.
     */
    else if (be16_to_cpu(leaf->hdr.stale)) {
        lfloglow = be16_to_cpu(leaf->hdr.count);
        lfloghigh = -1;
    }
    /*
     * If there was no data block space found, we need to allocate
     * a new one.
     */
    if (use_block == -1) {
        /*
         * Add the new data block.
         */
        if ((error = xfs_dir2_grow_inode(args, XFS_DIR2_DATA_SPACE,
                &use_block))) {
            xfs_trans_brelse(tp, lbp);
            return error;
        }
        /*
         * Initialize the block.
         */
        if ((error = xfs_dir2_data_init(args, use_block, &dbp))) {
            xfs_trans_brelse(tp, lbp);
            return error;
        }
        /*
         * If we're adding a new data block on the end we need to
         * extend the bests table.  Copy it up one entry.
         */
        if (use_block >= be32_to_cpu(ltp->bestcount)) {
            bestsp--;
            memmove(&bestsp[0], &bestsp[1],
                be32_to_cpu(ltp->bestcount) * sizeof(bestsp[0]));
            be32_add_cpu(&ltp->bestcount, 1);
            xfs_dir2_leaf_log_tail(tp, lbp);
            xfs_dir2_leaf_log_bests(tp, lbp, 0, be32_to_cpu(ltp->bestcount) - 1);
        }
        /*
         * If we're filling in a previously empty block just log it.
         */
        else
            xfs_dir2_leaf_log_bests(tp, lbp, use_block, use_block);
        hdr = dbp->b_addr;
        bestsp[use_block] = hdr->bestfree[0].length;
        grown = 1;
    }
    /*
     * Already had space in some data block.
     * Just read that one in.
     */
    else {
        if ((error =
            xfs_da_read_buf(tp, dp, xfs_dir2_db_to_da(mp, use_block),
                -1, &dbp, XFS_DATA_FORK))) {
            xfs_trans_brelse(tp, lbp);
            return error;
        }
        hdr = dbp->b_addr;
        grown = 0;
    }
    xfs_dir2_data_check(dp, dbp);
    /*
     * Point to the biggest freespace in our data block.
     */
    dup = (xfs_dir2_data_unused_t *)
          ((char *)hdr + be16_to_cpu(hdr->bestfree[0].offset));
    ASSERT(be16_to_cpu(dup->length) >= length);
    needscan = needlog = 0;
    /*
     * Mark the initial part of our freespace in use for the new entry.
     */
    xfs_dir2_data_use_free(tp, dbp, dup,
        (xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr), length,
        &needlog, &needscan);
    /*
     * Initialize our new entry (at last).
     */
    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);
    /*
     * Need to scan fix up the bestfree table.
     */
    if (needscan)
        xfs_dir2_data_freescan(mp, hdr, &needlog);
    /*
     * Need to log the data block's header.
     */
    if (needlog)
        xfs_dir2_data_log_header(tp, dbp);
    xfs_dir2_data_log_entry(tp, dbp, dep);
    /*
     * If the bests table needs to be changed, do it.
     * Log the change unless we've already done that.
     */
    if (be16_to_cpu(bestsp[use_block]) != be16_to_cpu(hdr->bestfree[0].length)) {
        bestsp[use_block] = hdr->bestfree[0].length;
        if (!grown)
            xfs_dir2_leaf_log_bests(tp, lbp, use_block, use_block);
    }

    lep = xfs_dir2_leaf_find_entry(leaf, index, compact, lowstale,
                       highstale, &lfloglow, &lfloghigh);

    /*
     * Fill in the new leaf entry.
     */
    lep->hashval = cpu_to_be32(args->hashval);
    lep->address = cpu_to_be32(xfs_dir2_db_off_to_dataptr(mp, use_block,
                be16_to_cpu(*tagp)));
    /*
     * Log the leaf fields and give up the buffers.
     */
    xfs_dir2_leaf_log_header(tp, lbp);
    xfs_dir2_leaf_log_ents(tp, lbp, lfloglow, lfloghigh);
    xfs_dir2_leaf_check(dp, lbp);
    xfs_dir2_data_check(dp, dbp);
    return 0;
}

#ifdef DEBUG
/*
 * Check the internal consistency of a leaf1 block.
 * Pop an assert if something is wrong.
 */
STATIC void
xfs_dir2_leaf_check(
    struct xfs_inode    *dp,        /* incore directory inode */
    struct xfs_buf      *bp)        /* leaf's buffer */
{
    int         i;      /* leaf index */
    xfs_dir2_leaf_t     *leaf;      /* leaf structure */
    xfs_dir2_leaf_tail_t    *ltp;       /* leaf tail pointer */
    xfs_mount_t     *mp;        /* filesystem mount point */
    int         stale;      /* count of stale leaves */

    leaf = bp->b_addr;
    mp = dp->i_mount;
    ASSERT(leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAF1_MAGIC));
    /*
     * This value is not restrictive enough.
     * Should factor in the size of the bests table as well.
     * We can deduce a value for that from di_size.
     */
    ASSERT(be16_to_cpu(leaf->hdr.count) <= xfs_dir2_max_leaf_ents(mp));
    ltp = xfs_dir2_leaf_tail_p(mp, leaf);
    /*
     * Leaves and bests don't overlap.
     */
    ASSERT((char *)&leaf->ents[be16_to_cpu(leaf->hdr.count)] <=
           (char *)xfs_dir2_leaf_bests_p(ltp));
    /*
     * Check hash value order, count stale entries.
     */
    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 */

/*
 * Compact out any stale entries in the leaf.
 * Log the header and changed leaf entries, if any.
 */
void
xfs_dir2_leaf_compact(
    xfs_da_args_t   *args,      /* operation arguments */
    struct xfs_buf  *bp)        /* leaf buffer */
{
    int     from;       /* source leaf index */
    xfs_dir2_leaf_t *leaf;      /* leaf structure */
    int     loglow;     /* first leaf entry to log */
    int     to;     /* target leaf index */

    leaf = bp->b_addr;
    if (!leaf->hdr.stale) {
        return;
    }
    /*
     * Compress out the stale entries in place.
     */
    for (from = to = 0, loglow = -1; from < be16_to_cpu(leaf->hdr.count); from++) {
        if (leaf->ents[from].address ==
            cpu_to_be32(XFS_DIR2_NULL_DATAPTR))
            continue;
        /*
         * Only actually copy the entries that are different.
         */
        if (from > to) {
            if (loglow == -1)
                loglow = to;
            leaf->ents[to] = leaf->ents[from];
        }
        to++;
    }
    /*
     * Update and log the header, log the leaf entries.
     */
    ASSERT(be16_to_cpu(leaf->hdr.stale) == from - to);
    be16_add_cpu(&leaf->hdr.count, -(be16_to_cpu(leaf->hdr.stale)));
    leaf->hdr.stale = 0;
    xfs_dir2_leaf_log_header(args->trans, bp);
    if (loglow != -1)
        xfs_dir2_leaf_log_ents(args->trans, bp, loglow, to - 1);
}

/*
 * Compact the leaf entries, removing stale ones.
 * Leave one stale entry behind - the one closest to our
 * insertion index - and the caller will shift that one to our insertion
 * point later.
 * Return new insertion index, where the remaining stale entry is,
 * and leaf logging indices.
 */
void
xfs_dir2_leaf_compact_x1(
    struct xfs_buf  *bp,        /* leaf buffer */
    int     *indexp,    /* insertion index */
    int     *lowstalep, /* out: stale entry before us */
    int     *highstalep,    /* out: stale entry after us */
    int     *lowlogp,   /* out: low log index */
    int     *highlogp)  /* out: high log index */
{
    int     from;       /* source copy index */
    int     highstale;  /* stale entry at/after index */
    int     index;      /* insertion index */
    int     keepstale;  /* source index of kept stale */
    xfs_dir2_leaf_t *leaf;      /* leaf structure */
    int     lowstale;   /* stale entry before index */
    int     newindex=0; /* new insertion index */
    int     to;     /* destination copy index */

    leaf = bp->b_addr;
    ASSERT(be16_to_cpu(leaf->hdr.stale) > 1);
    index = *indexp;

    xfs_dir2_leaf_find_stale(leaf, index, &lowstale, &highstale);

    /*
     * Pick the better of lowstale and highstale.
     */
    if (lowstale >= 0 &&
        (highstale == be16_to_cpu(leaf->hdr.count) ||
         index - lowstale <= highstale - index))
        keepstale = lowstale;
    else
        keepstale = highstale;
    /*
     * Copy the entries in place, removing all the stale entries
     * except keepstale.
     */
    for (from = to = 0; from < be16_to_cpu(leaf->hdr.count); from++) {
        /*
         * Notice the new value of index.
         */
        if (index == from)
            newindex = to;
        if (from != keepstale &&
            leaf->ents[from].address ==
            cpu_to_be32(XFS_DIR2_NULL_DATAPTR)) {
            if (from == to)
                *lowlogp = to;
            continue;
        }
        /*
         * Record the new keepstale value for the insertion.
         */
        if (from == keepstale)
            lowstale = highstale = to;
        /*
         * Copy only the entries that have moved.
         */
        if (from > to)
            leaf->ents[to] = leaf->ents[from];
        to++;
    }
    ASSERT(from > to);
    /*
     * If the insertion point was past the last entry,
     * set the new insertion point accordingly.
     */
    if (index == from)
        newindex = to;
    *indexp = newindex;
    /*
     * Adjust the leaf header values.
     */
    be16_add_cpu(&leaf->hdr.count, -(from - to));
    leaf->hdr.stale = cpu_to_be16(1);
    /*
     * Remember the low/high stale value only in the "right"
     * direction.
     */
    if (lowstale >= newindex)
        lowstale = -1;
    else
        highstale = be16_to_cpu(leaf->hdr.count);
    *highlogp = be16_to_cpu(leaf->hdr.count) - 1;
    *lowstalep = lowstale;
    *highstalep = highstale;
}

struct xfs_dir2_leaf_map_info {
    xfs_extlen_t    map_blocks; /* number of fsbs in map */
    xfs_dablk_t map_off;    /* last mapped file offset */
    int     map_size;   /* total entries in *map */
    int     map_valid;  /* valid entries in *map */
    int     nmap;       /* mappings to ask xfs_bmapi */
    xfs_dir2_db_t   curdb;      /* db for current block */
    int     ra_current; /* number of read-ahead blks */
    int     ra_index;   /* *map index for read-ahead */
    int     ra_offset;  /* map entry offset for ra */
    int     ra_want;    /* readahead count wanted */
    struct xfs_bmbt_irec map[]; /* map vector for blocks */
};

STATIC int
xfs_dir2_leaf_readbuf(
    struct xfs_inode    *dp,
    size_t          bufsize,
    struct xfs_dir2_leaf_map_info *mip,
    xfs_dir2_off_t      *curoff,
    struct xfs_buf      **bpp)
{
    struct xfs_mount    *mp = dp->i_mount;
    struct xfs_buf      *bp = *bpp;
    struct xfs_bmbt_irec    *map = mip->map;
    int         error = 0;
    int         length;
    int         i;
    int         j;

    /*
     * If we have a buffer, we need to release it and
     * take it out of the mapping.
     */

    if (bp) {
        xfs_trans_brelse(NULL, bp);
        bp = NULL;
        mip->map_blocks -= mp->m_dirblkfsbs;
        /*
         * Loop to get rid of the extents for the
         * directory block.
         */
        for (i = mp->m_dirblkfsbs; i > 0; ) {
            j = min_t(int, map->br_blockcount, i);
            map->br_blockcount -= j;
            map->br_startblock += j;
            map->br_startoff += j;
            /*
             * If mapping is done, pitch it from
             * the table.
             */
            if (!map->br_blockcount && --mip->map_valid)
                memmove(&map[0], &map[1],
                    sizeof(map[0]) * mip->map_valid);
            i -= j;
        }
    }

    /*
     * Recalculate the readahead blocks wanted.
     */
    mip->ra_want = howmany(bufsize + mp->m_dirblksize,
                   mp->m_sb.sb_blocksize) - 1;
    ASSERT(mip->ra_want >= 0);

    /*
     * If we don't have as many as we want, and we haven't
     * run out of data blocks, get some more mappings.
     */
    if (1 + mip->ra_want > mip->map_blocks &&
        mip->map_off < xfs_dir2_byte_to_da(mp, XFS_DIR2_LEAF_OFFSET)) {
        /*
         * Get more bmaps, fill in after the ones
         * we already have in the table.
         */
        mip->nmap = mip->map_size - mip->map_valid;
        error = xfs_bmapi_read(dp, mip->map_off,
                xfs_dir2_byte_to_da(mp, XFS_DIR2_LEAF_OFFSET) -
                                mip->map_off,
                &map[mip->map_valid], &mip->nmap, 0);

        /*
         * Don't know if we should ignore this or try to return an
         * error.  The trouble with returning errors is that readdir
         * will just stop without actually passing the error through.
         */
        if (error)
            goto out;   /* XXX */

        /*
         * If we got all the mappings we asked for, set the final map
         * offset based on the last bmap value received.  Otherwise,
         * we've reached the end.
         */
        if (mip->nmap == mip->map_size - mip->map_valid) {
            i = mip->map_valid + mip->nmap - 1;
            mip->map_off = map[i].br_startoff + map[i].br_blockcount;
        } else
            mip->map_off = xfs_dir2_byte_to_da(mp,
                            XFS_DIR2_LEAF_OFFSET);

        /*
         * Look for holes in the mapping, and eliminate them.  Count up
         * the valid blocks.
         */
        for (i = mip->map_valid; i < mip->map_valid + mip->nmap; ) {
            if (map[i].br_startblock == HOLESTARTBLOCK) {
                mip->nmap--;
                length = mip->map_valid + mip->nmap - i;
                if (length)
                    memmove(&map[i], &map[i + 1],
                        sizeof(map[i]) * length);
            } else {
                mip->map_blocks += map[i].br_blockcount;
                i++;
            }
        }
        mip->map_valid += mip->nmap;
    }

    /*
     * No valid mappings, so no more data blocks.
     */
    if (!mip->map_valid) {
        *curoff = xfs_dir2_da_to_byte(mp, mip->map_off);
        goto out;
    }

    /*
     * Read the directory block starting at the first mapping.
     */
    mip->curdb = xfs_dir2_da_to_db(mp, map->br_startoff);
    error = xfs_da_read_buf(NULL, dp, map->br_startoff,
            map->br_blockcount >= mp->m_dirblkfsbs ?
                XFS_FSB_TO_DADDR(mp, map->br_startblock) : -1,
            &bp, XFS_DATA_FORK);

    /*
     * Should just skip over the data block instead of giving up.
     */
    if (error)
        goto out;   /* XXX */

    /*
     * Adjust the current amount of read-ahead: we just read a block that
     * was previously ra.
     */
    if (mip->ra_current)
        mip->ra_current -= mp->m_dirblkfsbs;

    /*
     * Do we need more readahead?
     */
    for (mip->ra_index = mip->ra_offset = i = 0;
         mip->ra_want > mip->ra_current && i < mip->map_blocks;
         i += mp->m_dirblkfsbs) {
        ASSERT(mip->ra_index < mip->map_valid);
        /*
         * Read-ahead a contiguous directory block.
         */
        if (i > mip->ra_current &&
            map[mip->ra_index].br_blockcount >= mp->m_dirblkfsbs) {
            xfs_buf_readahead(mp->m_ddev_targp,
                XFS_FSB_TO_DADDR(mp,
                    map[mip->ra_index].br_startblock +
                            mip->ra_offset),
                (int)BTOBB(mp->m_dirblksize));
            mip->ra_current = i;
        }

        /*
         * Read-ahead a non-contiguous directory block.  This doesn't
         * use our mapping, but this is a very rare case.
         */
        else if (i > mip->ra_current) {
            xfs_da_reada_buf(NULL, dp,
                    map[mip->ra_index].br_startoff +
                            mip->ra_offset,
                    XFS_DATA_FORK);
            mip->ra_current = i;
        }

        /*
         * Advance offset through the mapping table.
         */
        for (j = 0; j < mp->m_dirblkfsbs; j++) {
            /*
             * The rest of this extent but not more than a dir
             * block.
             */
            length = min_t(int, mp->m_dirblkfsbs,
                    map[mip->ra_index].br_blockcount -
                            mip->ra_offset);
            j += length;
            mip->ra_offset += length;

            /*
             * Advance to the next mapping if this one is used up.
             */
            if (mip->ra_offset == map[mip->ra_index].br_blockcount) {
                mip->ra_offset = 0;
                mip->ra_index++;
            }
        }
    }

out:
    *bpp = bp;
    return error;
}

/*
 * Getdents (readdir) for leaf and node directories.
 * This reads the data blocks only, so is the same for both forms.
 */
int                     /* error */
xfs_dir2_leaf_getdents(
    xfs_inode_t     *dp,        /* incore directory inode */
    void            *dirent,
    size_t          bufsize,
    xfs_off_t       *offset,
    filldir_t       filldir)
{
    struct xfs_buf      *bp = NULL; /* data block buffer */
    xfs_dir2_data_hdr_t *hdr;       /* data block header */
    xfs_dir2_data_entry_t   *dep;       /* data entry */
    xfs_dir2_data_unused_t  *dup;       /* unused entry */
    int         error = 0;  /* error return value */
    int         length;     /* temporary length value */
    xfs_mount_t     *mp;        /* filesystem mount point */
    int         byteoff;    /* offset in current block */
    xfs_dir2_off_t      curoff;     /* current overall offset */
    xfs_dir2_off_t      newoff;     /* new curoff after new blk */
    char            *ptr = NULL;    /* pointer to current data */
    struct xfs_dir2_leaf_map_info *map_info;

    /*
     * If the offset is at or past the largest allowed value,
     * give up right away.
     */
    if (*offset >= XFS_DIR2_MAX_DATAPTR)
        return 0;

    mp = dp->i_mount;

    /*
     * Set up to bmap a number of blocks based on the caller's
     * buffer size, the directory block size, and the filesystem
     * block size.
     */
    length = howmany(bufsize + mp->m_dirblksize,
                     mp->m_sb.sb_blocksize);
    map_info = kmem_zalloc(offsetof(struct xfs_dir2_leaf_map_info, map) +
                (length * sizeof(struct xfs_bmbt_irec)),
                   KM_SLEEP);
    map_info->map_size = length;

    /*
     * Inside the loop we keep the main offset value as a byte offset
     * in the directory file.
     */
    curoff = xfs_dir2_dataptr_to_byte(mp, *offset);

    /*
     * Force this conversion through db so we truncate the offset
     * down to get the start of the data block.
     */
    map_info->map_off = xfs_dir2_db_to_da(mp,
                          xfs_dir2_byte_to_db(mp, curoff));

    /*
     * Loop over directory entries until we reach the end offset.
     * Get more blocks and readahead as necessary.
     */
    while (curoff < XFS_DIR2_LEAF_OFFSET) {
        /*
         * If we have no buffer, or we're off the end of the
         * current buffer, need to get another one.
         */
        if (!bp || ptr >= (char *)bp->b_addr + mp->m_dirblksize) {

            error = xfs_dir2_leaf_readbuf(dp, bufsize, map_info,
                              &curoff, &bp);
            if (error || !map_info->map_valid)
                break;

            /*
             * Having done a read, we need to set a new offset.
             */
            newoff = xfs_dir2_db_off_to_byte(mp, map_info->curdb, 0);
            /*
             * Start of the current block.
             */
            if (curoff < newoff)
                curoff = newoff;
            /*
             * Make sure we're in the right block.
             */
            else if (curoff > newoff)
                ASSERT(xfs_dir2_byte_to_db(mp, curoff) ==
                       map_info->curdb);
            hdr = bp->b_addr;
            xfs_dir2_data_check(dp, bp);
            /*
             * Find our position in the block.
             */
            ptr = (char *)(hdr + 1);
            byteoff = xfs_dir2_byte_to_off(mp, curoff);
            /*
             * Skip past the header.
             */
            if (byteoff == 0)
                curoff += (uint)sizeof(*hdr);
            /*
             * Skip past entries until we reach our offset.
             */
            else {
                while ((char *)ptr - (char *)hdr < byteoff) {
                    dup = (xfs_dir2_data_unused_t *)ptr;

                    if (be16_to_cpu(dup->freetag)
                          == XFS_DIR2_DATA_FREE_TAG) {

                        length = be16_to_cpu(dup->length);
                        ptr += length;
                        continue;
                    }
                    dep = (xfs_dir2_data_entry_t *)ptr;
                    length =
                       xfs_dir2_data_entsize(dep->namelen);
                    ptr += length;
                }
                /*
                 * Now set our real offset.
                 */
                curoff =
                    xfs_dir2_db_off_to_byte(mp,
                        xfs_dir2_byte_to_db(mp, curoff),
                        (char *)ptr - (char *)hdr);
                if (ptr >= (char *)hdr + mp->m_dirblksize) {
                    continue;
                }
            }
        }
        /*
         * We have a pointer to an entry.
         * Is it a live one?
         */
        dup = (xfs_dir2_data_unused_t *)ptr;
        /*
         * No, it's unused, skip over it.
         */
        if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
            length = be16_to_cpu(dup->length);
            ptr += length;
            curoff += length;
            continue;
        }

        dep = (xfs_dir2_data_entry_t *)ptr;
        length = xfs_dir2_data_entsize(dep->namelen);

        if (filldir(dirent, (char *)dep->name, dep->namelen,
                xfs_dir2_byte_to_dataptr(mp, curoff) & 0x7fffffff,
                be64_to_cpu(dep->inumber), DT_UNKNOWN))
            break;

        /*
         * Advance to next entry in the block.
         */
        ptr += length;
        curoff += length;
        /* bufsize may have just been a guess; don't go negative */
        bufsize = bufsize > length ? bufsize - length : 0;
    }

    /*
     * All done.  Set output offset value to current offset.
     */
    if (curoff > xfs_dir2_dataptr_to_byte(mp, XFS_DIR2_MAX_DATAPTR))
        *offset = XFS_DIR2_MAX_DATAPTR & 0x7fffffff;
    else
        *offset = xfs_dir2_byte_to_dataptr(mp, curoff) & 0x7fffffff;
    kmem_free(map_info);
    if (bp)
        xfs_trans_brelse(NULL, bp);
    return error;
}

/*
 * Initialize a new leaf block, leaf1 or leafn magic accepted.
 */
int
xfs_dir2_leaf_init(
    xfs_da_args_t       *args,      /* operation arguments */
    xfs_dir2_db_t       bno,        /* directory block number */
    struct xfs_buf      **bpp,      /* out: leaf buffer */
    int         magic)      /* magic number for block */
{
    struct xfs_buf      *bp;        /* leaf buffer */
    xfs_inode_t     *dp;        /* incore directory inode */
    int         error;      /* error return code */
    xfs_dir2_leaf_t     *leaf;      /* leaf structure */
    xfs_dir2_leaf_tail_t    *ltp;       /* leaf tail structure */
    xfs_mount_t     *mp;        /* filesystem mount point */
    xfs_trans_t     *tp;        /* transaction pointer */

    dp = args->dp;
    ASSERT(dp != NULL);
    tp = args->trans;
    mp = dp->i_mount;
    ASSERT(bno >= XFS_DIR2_LEAF_FIRSTDB(mp) &&
           bno < XFS_DIR2_FREE_FIRSTDB(mp));
    /*
     * Get the buffer for the block.
     */
    error = xfs_da_get_buf(tp, dp, xfs_dir2_db_to_da(mp, bno), -1, &bp,
        XFS_DATA_FORK);
    if (error) {
        return error;
    }
    ASSERT(bp != NULL);
    leaf = bp->b_addr;
    /*
     * Initialize the header.
     */
    leaf->hdr.info.magic = cpu_to_be16(magic);
    leaf->hdr.info.forw = 0;
    leaf->hdr.info.back = 0;
    leaf->hdr.count = 0;
    leaf->hdr.stale = 0;
    xfs_dir2_leaf_log_header(tp, bp);
    /*
     * If it's a leaf-format directory initialize the tail.
     * In this case our caller has the real bests table to copy into
     * the block.
     */
    if (magic == XFS_DIR2_LEAF1_MAGIC) {
        ltp = xfs_dir2_leaf_tail_p(mp, leaf);
        ltp->bestcount = 0;
        xfs_dir2_leaf_log_tail(tp, bp);
    }
    *bpp = bp;
    return 0;
}

/*
 * Log the bests entries indicated from a leaf1 block.
 */
static void
xfs_dir2_leaf_log_bests(
    xfs_trans_t     *tp,        /* transaction pointer */
    struct xfs_buf      *bp,        /* leaf buffer */
    int         first,      /* first entry to log */
    int         last)       /* last entry to log */
{
    __be16          *firstb;    /* pointer to first entry */
    __be16          *lastb;     /* pointer to last entry */
    xfs_dir2_leaf_t     *leaf;      /* leaf structure */
    xfs_dir2_leaf_tail_t    *ltp;       /* leaf tail structure */

    leaf = bp->b_addr;
    ASSERT(leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAF1_MAGIC));
    ltp = xfs_dir2_leaf_tail_p(tp->t_mountp, leaf);
    firstb = xfs_dir2_leaf_bests_p(ltp) + first;
    lastb = xfs_dir2_leaf_bests_p(ltp) + last;
    xfs_trans_log_buf(tp, bp, (uint)((char *)firstb - (char *)leaf),
        (uint)((char *)lastb - (char *)leaf + sizeof(*lastb) - 1));
}

/*
 * Log the leaf entries indicated from a leaf1 or leafn block.
 */
void
xfs_dir2_leaf_log_ents(
    xfs_trans_t     *tp,        /* transaction pointer */
    struct xfs_buf      *bp,        /* leaf buffer */
    int         first,      /* first entry to log */
    int         last)       /* last entry to log */
{
    xfs_dir2_leaf_entry_t   *firstlep;  /* pointer to first entry */
    xfs_dir2_leaf_entry_t   *lastlep;   /* pointer to last entry */
    xfs_dir2_leaf_t     *leaf;      /* leaf structure */

    leaf = bp->b_addr;
    ASSERT(leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAF1_MAGIC) ||
           leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAFN_MAGIC));
    firstlep = &leaf->ents[first];
    lastlep = &leaf->ents[last];
    xfs_trans_log_buf(tp, bp, (uint)((char *)firstlep - (char *)leaf),
        (uint)((char *)lastlep - (char *)leaf + sizeof(*lastlep) - 1));
}

/*
 * Log the header of the leaf1 or leafn block.
 */
void
xfs_dir2_leaf_log_header(
    struct xfs_trans    *tp,
    struct xfs_buf      *bp)
{
    xfs_dir2_leaf_t     *leaf;      /* leaf structure */

    leaf = bp->b_addr;
    ASSERT(leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAF1_MAGIC) ||
           leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAFN_MAGIC));
    xfs_trans_log_buf(tp, bp, (uint)((char *)&leaf->hdr - (char *)leaf),
        (uint)(sizeof(leaf->hdr) - 1));
}

/*
 * Log the tail of the leaf1 block.
 */
STATIC void
xfs_dir2_leaf_log_tail(
    struct xfs_trans    *tp,
    struct xfs_buf      *bp)
{
    xfs_dir2_leaf_t     *leaf;      /* leaf structure */
    xfs_dir2_leaf_tail_t    *ltp;       /* leaf tail structure */
    xfs_mount_t     *mp;        /* filesystem mount point */

    mp = tp->t_mountp;
    leaf = bp->b_addr;
    ASSERT(leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAF1_MAGIC));
    ltp = xfs_dir2_leaf_tail_p(mp, leaf);
    xfs_trans_log_buf(tp, bp, (uint)((char *)ltp - (char *)leaf),
        (uint)(mp->m_dirblksize - 1));
}

/*
 * Look up the entry referred to by args in the leaf format directory.
 * Most of the work is done by the xfs_dir2_leaf_lookup_int routine which
 * is also used by the node-format code.
 */
int
xfs_dir2_leaf_lookup(
    xfs_da_args_t       *args)      /* operation arguments */
{
    struct xfs_buf      *dbp;       /* data block buffer */
    xfs_dir2_data_entry_t   *dep;       /* data block entry */
    xfs_inode_t     *dp;        /* incore directory inode */
    int         error;      /* error return code */
    int         index;      /* found entry index */
    struct xfs_buf      *lbp;       /* leaf buffer */
    xfs_dir2_leaf_t     *leaf;      /* leaf structure */
    xfs_dir2_leaf_entry_t   *lep;       /* leaf entry */
    xfs_trans_t     *tp;        /* transaction pointer */

    trace_xfs_dir2_leaf_lookup(args);

    /*
     * Look up name in the leaf block, returning both buffers and index.
     */
    if ((error = xfs_dir2_leaf_lookup_int(args, &lbp, &index, &dbp))) {
        return error;
    }
    tp = args->trans;
    dp = args->dp;
    xfs_dir2_leaf_check(dp, lbp);
    leaf = lbp->b_addr;
    /*
     * Get to the leaf entry and contained data entry address.
     */
    lep = &leaf->ents[index];
    /*
     * Point to the data entry.
     */
    dep = (xfs_dir2_data_entry_t *)
          ((char *)dbp->b_addr +
           xfs_dir2_dataptr_to_off(dp->i_mount, be32_to_cpu(lep->address)));
    /*
     * Return the found inode number & CI name if appropriate
     */
    args->inumber = be64_to_cpu(dep->inumber);
    error = xfs_dir_cilookup_result(args, dep->name, dep->namelen);
    xfs_trans_brelse(tp, dbp);
    xfs_trans_brelse(tp, lbp);
    return XFS_ERROR(error);
}

/*
 * Look up name/hash in the leaf block.
 * Fill in indexp with the found index, and dbpp with the data buffer.
 * If not found dbpp will be NULL, and ENOENT comes back.
 * lbpp will always be filled in with the leaf buffer unless there's an error.
 */
static int                  /* error */
xfs_dir2_leaf_lookup_int(
    xfs_da_args_t       *args,      /* operation arguments */
    struct xfs_buf      **lbpp,     /* out: leaf buffer */
    int         *indexp,    /* out: index in leaf block */
    struct xfs_buf      **dbpp)     /* out: data buffer */
{
    xfs_dir2_db_t       curdb = -1; /* current data block number */
    struct xfs_buf      *dbp = NULL;    /* data buffer */
    xfs_dir2_data_entry_t   *dep;       /* data entry */
    xfs_inode_t     *dp;        /* incore directory inode */
    int         error;      /* error return code */
    int         index;      /* index in leaf block */
    struct xfs_buf      *lbp;       /* leaf buffer */
    xfs_dir2_leaf_entry_t   *lep;       /* leaf entry */
    xfs_dir2_leaf_t     *leaf;      /* leaf structure */
    xfs_mount_t     *mp;        /* filesystem mount point */
    xfs_dir2_db_t       newdb;      /* new data block number */
    xfs_trans_t     *tp;        /* transaction pointer */
    xfs_dir2_db_t       cidb = -1;  /* case match data block no. */
    enum xfs_dacmp      cmp;        /* name compare result */

    dp = args->dp;
    tp = args->trans;
    mp = dp->i_mount;
    /*
     * Read the leaf block into the buffer.
     */
    error = xfs_da_read_buf(tp, dp, mp->m_dirleafblk, -1, &lbp,
                            XFS_DATA_FORK);
    if (error)
        return error;
    *lbpp = lbp;
    leaf = lbp->b_addr;
    xfs_dir2_leaf_check(dp, lbp);
    /*
     * Look for the first leaf entry with our hash value.
     */
    index = xfs_dir2_leaf_search_hash(args, lbp);
    /*
     * Loop over all the entries with the right hash value
     * looking to match the name.
     */
    for (lep = &leaf->ents[index]; index < be16_to_cpu(leaf->hdr.count) &&
                be32_to_cpu(lep->hashval) == args->hashval;
                lep++, index++) {
        /*
         * Skip over stale leaf entries.
         */
        if (be32_to_cpu(lep->address) == XFS_DIR2_NULL_DATAPTR)
            continue;
        /*
         * Get the new data block number.
         */
        newdb = xfs_dir2_dataptr_to_db(mp, be32_to_cpu(lep->address));
        /*
         * If it's not the same as the old data block number,
         * need to pitch the old one and read the new one.
         */
        if (newdb != curdb) {
            if (dbp)
                xfs_trans_brelse(tp, dbp);
            error = xfs_da_read_buf(tp, dp,
                        xfs_dir2_db_to_da(mp, newdb),
                        -1, &dbp, XFS_DATA_FORK);
            if (error) {
                xfs_trans_brelse(tp, lbp);
                return error;
            }
            xfs_dir2_data_check(dp, dbp);
            curdb = newdb;
        }
        /*
         * Point to the data entry.
         */
        dep = (xfs_dir2_data_entry_t *)((char *)dbp->b_addr +
            xfs_dir2_dataptr_to_off(mp, be32_to_cpu(lep->address)));
        /*
         * Compare name and if it's an exact match, return the index
         * and buffer. If it's the first case-insensitive match, store
         * the index and buffer and continue looking for an exact match.
         */
        cmp = mp->m_dirnameops->compname(args, dep->name, dep->namelen);
        if (cmp != XFS_CMP_DIFFERENT && cmp != args->cmpresult) {
            args->cmpresult = cmp;
            *indexp = index;
            /* case exact match: return the current buffer. */
            if (cmp == XFS_CMP_EXACT) {
                *dbpp = dbp;
                return 0;
            }
            cidb = curdb;
        }
    }
    ASSERT(args->op_flags & XFS_DA_OP_OKNOENT);
    /*
     * Here, we can only be doing a lookup (not a rename or remove).
     * If a case-insensitive match was found earlier, re-read the
     * appropriate data block if required and return it.
     */
    if (args->cmpresult == XFS_CMP_CASE) {
        ASSERT(cidb != -1);
        if (cidb != curdb) {
            xfs_trans_brelse(tp, dbp);
            error = xfs_da_read_buf(tp, dp,
                        xfs_dir2_db_to_da(mp, cidb),
                        -1, &dbp, XFS_DATA_FORK);
            if (error) {
                xfs_trans_brelse(tp, lbp);
                return error;
            }
        }
        *dbpp = dbp;
        return 0;
    }
    /*
     * No match found, return ENOENT.
     */
    ASSERT(cidb == -1);
    if (dbp)
        xfs_trans_brelse(tp, dbp);
    xfs_trans_brelse(tp, lbp);
    return XFS_ERROR(ENOENT);
}

/*
 * Remove an entry from a leaf format directory.
 */
int                     /* error */
xfs_dir2_leaf_removename(
    xfs_da_args_t       *args)      /* operation arguments */
{
    __be16          *bestsp;    /* leaf block best freespace */
    xfs_dir2_data_hdr_t *hdr;       /* data block header */
    xfs_dir2_db_t       db;     /* data block number */
    struct xfs_buf      *dbp;       /* data block buffer */
    xfs_dir2_data_entry_t   *dep;       /* data entry structure */
    xfs_inode_t     *dp;        /* incore directory inode */
    int         error;      /* error return code */
    xfs_dir2_db_t       i;      /* temporary data block # */
    int         index;      /* index into leaf entries */
    struct xfs_buf      *lbp;       /* leaf buffer */
    xfs_dir2_leaf_t     *leaf;      /* leaf structure */
    xfs_dir2_leaf_entry_t   *lep;       /* leaf entry */
    xfs_dir2_leaf_tail_t    *ltp;       /* leaf tail structure */
    xfs_mount_t     *mp;        /* filesystem mount point */
    int         needlog;    /* need to log data header */
    int         needscan;   /* need to rescan data frees */
    xfs_dir2_data_off_t oldbest;    /* old value of best free */
    xfs_trans_t     *tp;        /* transaction pointer */

    trace_xfs_dir2_leaf_removename(args);

    /*
     * Lookup the leaf entry, get the leaf and data blocks read in.
     */
    if ((error = xfs_dir2_leaf_lookup_int(args, &lbp, &index, &dbp))) {
        return error;
    }
    dp = args->dp;
    tp = args->trans;
    mp = dp->i_mount;
    leaf = lbp->b_addr;
    hdr = dbp->b_addr;
    xfs_dir2_data_check(dp, dbp);
    /*
     * Point to the leaf entry, use that to point to the data entry.
     */
    lep = &leaf->ents[index];
    db = xfs_dir2_dataptr_to_db(mp, be32_to_cpu(lep->address));
    dep = (xfs_dir2_data_entry_t *)
          ((char *)hdr + xfs_dir2_dataptr_to_off(mp, be32_to_cpu(lep->address)));
    needscan = needlog = 0;
    oldbest = be16_to_cpu(hdr->bestfree[0].length);
    ltp = xfs_dir2_leaf_tail_p(mp, leaf);
    bestsp = xfs_dir2_leaf_bests_p(ltp);
    ASSERT(be16_to_cpu(bestsp[db]) == oldbest);
    /*
     * Mark the former data entry unused.
     */
    xfs_dir2_data_make_free(tp, dbp,
        (xfs_dir2_data_aoff_t)((char *)dep - (char *)hdr),
        xfs_dir2_data_entsize(dep->namelen), &needlog, &needscan);
    /*
     * We just mark the leaf entry stale by putting a null in it.
     */
    be16_add_cpu(&leaf->hdr.stale, 1);
    xfs_dir2_leaf_log_header(tp, lbp);
    lep->address = cpu_to_be32(XFS_DIR2_NULL_DATAPTR);
    xfs_dir2_leaf_log_ents(tp, lbp, index, index);
    /*
     * Scan the freespace in the data block again if necessary,
     * log the data block header if necessary.
     */
    if (needscan)
        xfs_dir2_data_freescan(mp, hdr, &needlog);
    if (needlog)
        xfs_dir2_data_log_header(tp, dbp);
    /*
     * If the longest freespace in the data block has changed,
     * put the new value in the bests table and log that.
     */
    if (be16_to_cpu(hdr->bestfree[0].length) != oldbest) {
        bestsp[db] = hdr->bestfree[0].length;
        xfs_dir2_leaf_log_bests(tp, lbp, db, db);
    }
    xfs_dir2_data_check(dp, dbp);
    /*
     * If the data block is now empty then get rid of the data block.
     */
    if (be16_to_cpu(hdr->bestfree[0].length) ==
        mp->m_dirblksize - (uint)sizeof(*hdr)) {
        ASSERT(db != mp->m_dirdatablk);
        if ((error = xfs_dir2_shrink_inode(args, db, dbp))) {
            /*
             * Nope, can't get rid of it because it caused
             * allocation of a bmap btree block to do so.
             * Just go on, returning success, leaving the
             * empty block in place.
             */
            if (error == ENOSPC && args->total == 0)
                error = 0;
            xfs_dir2_leaf_check(dp, lbp);
            return error;
        }
        dbp = NULL;
        /*
         * If this is the last data block then compact the
         * bests table by getting rid of entries.
         */
        if (db == be32_to_cpu(ltp->bestcount) - 1) {
            /*
             * Look for the last active entry (i).
             */
            for (i = db - 1; i > 0; i--) {
                if (bestsp[i] != cpu_to_be16(NULLDATAOFF))
                    break;
            }
            /*
             * Copy the table down so inactive entries at the
             * end are removed.
             */
            memmove(&bestsp[db - i], bestsp,
                (be32_to_cpu(ltp->bestcount) - (db - i)) * sizeof(*bestsp));
            be32_add_cpu(&ltp->bestcount, -(db - i));
            xfs_dir2_leaf_log_tail(tp, lbp);
            xfs_dir2_leaf_log_bests(tp, lbp, 0, be32_to_cpu(ltp->bestcount) - 1);
        } else
            bestsp[db] = cpu_to_be16(NULLDATAOFF);
    }
    /*
     * If the data block was not the first one, drop it.
     */
    else if (db != mp->m_dirdatablk)
        dbp = NULL;

    xfs_dir2_leaf_check(dp, lbp);
    /*
     * See if we can convert to block form.
     */
    return xfs_dir2_leaf_to_block(args, lbp, dbp);
}

/*
 * Replace the inode number in a leaf format directory entry.
 */
int                     /* error */
xfs_dir2_leaf_replace(
    xfs_da_args_t       *args)      /* operation arguments */
{
    struct xfs_buf      *dbp;       /* data block buffer */
    xfs_dir2_data_entry_t   *dep;       /* data block entry */
    xfs_inode_t     *dp;        /* incore directory inode */
    int         error;      /* error return code */
    int         index;      /* index of leaf entry */
    struct xfs_buf      *lbp;       /* leaf buffer */
    xfs_dir2_leaf_t     *leaf;      /* leaf structure */
    xfs_dir2_leaf_entry_t   *lep;       /* leaf entry */
    xfs_trans_t     *tp;        /* transaction pointer */

    trace_xfs_dir2_leaf_replace(args);

    /*
     * Look up the entry.
     */
    if ((error = xfs_dir2_leaf_lookup_int(args, &lbp, &index, &dbp))) {
        return error;
    }
    dp = args->dp;
    leaf = lbp->b_addr;
    /*
     * Point to the leaf entry, get data address from it.
     */
    lep = &leaf->ents[index];
    /*
     * Point to the data entry.
     */
    dep = (xfs_dir2_data_entry_t *)
          ((char *)dbp->b_addr +
           xfs_dir2_dataptr_to_off(dp->i_mount, be32_to_cpu(lep->address)));
    ASSERT(args->inumber != be64_to_cpu(dep->inumber));
    /*
     * Put the new inode number in, log it.
     */
    dep->inumber = cpu_to_be64(args->inumber);
    tp = args->trans;
    xfs_dir2_data_log_entry(tp, dbp, dep);
    xfs_dir2_leaf_check(dp, lbp);
    xfs_trans_brelse(tp, lbp);
    return 0;
}

/*
 * Return index in the leaf block (lbp) which is either the first
 * one with this hash value, or if there are none, the insert point
 * for that hash value.
 */
int                     /* index value */
xfs_dir2_leaf_search_hash(
    xfs_da_args_t       *args,      /* operation arguments */
    struct xfs_buf      *lbp)       /* leaf buffer */
{
    xfs_dahash_t        hash=0;     /* hash from this entry */
    xfs_dahash_t        hashwant;   /* hash value looking for */
    int         high;       /* high leaf index */
    int         low;        /* low leaf index */
    xfs_dir2_leaf_t     *leaf;      /* leaf structure */
    xfs_dir2_leaf_entry_t   *lep;       /* leaf entry */
    int         mid=0;      /* current leaf index */

    leaf = lbp->b_addr;
#ifndef __KERNEL__
    if (!leaf->hdr.count)
        return 0;
#endif
    /*
     * Note, the table cannot be empty, so we have to go through the loop.
     * Binary search the leaf entries looking for our hash value.
     */
    for (lep = leaf->ents, low = 0, high = be16_to_cpu(leaf->hdr.count) - 1,
        hashwant = args->hashval;
         low <= high; ) {
        mid = (low + high) >> 1;
        if ((hash = be32_to_cpu(lep[mid].hashval)) == hashwant)
            break;
        if (hash < hashwant)
            low = mid + 1;
        else
            high = mid - 1;
    }
    /*
     * Found one, back up through all the equal hash values.
     */
    if (hash == hashwant) {
        while (mid > 0 && be32_to_cpu(lep[mid - 1].hashval) == hashwant) {
            mid--;
        }
    }
    /*
     * Need to point to an entry higher than ours.
     */
    else if (hash < hashwant)
        mid++;
    return mid;
}

/*
 * Trim off a trailing data block.  We know it's empty since the leaf
 * freespace table says so.
 */
int                     /* error */
xfs_dir2_leaf_trim_data(
    xfs_da_args_t       *args,      /* operation arguments */
    struct xfs_buf      *lbp,       /* leaf buffer */
    xfs_dir2_db_t       db)     /* data block number */
{
    __be16          *bestsp;    /* leaf bests table */
    struct xfs_buf      *dbp;       /* data block buffer */
    xfs_inode_t     *dp;        /* incore directory inode */
    int         error;      /* error return value */
    xfs_dir2_leaf_t     *leaf;      /* leaf structure */
    xfs_dir2_leaf_tail_t    *ltp;       /* leaf tail 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 offending data block.  We need its buffer.
     */
    if ((error = xfs_da_read_buf(tp, dp, xfs_dir2_db_to_da(mp, db), -1, &dbp,
            XFS_DATA_FORK))) {
        return error;
    }

    leaf = lbp->b_addr;
    ltp = xfs_dir2_leaf_tail_p(mp, leaf);

#ifdef DEBUG
{
    struct xfs_dir2_data_hdr *hdr = dbp->b_addr;

    ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC));
    ASSERT(be16_to_cpu(hdr->bestfree[0].length) ==
           mp->m_dirblksize - (uint)sizeof(*hdr));
    ASSERT(db == be32_to_cpu(ltp->bestcount) - 1);
}
#endif

    /*
     * Get rid of the data block.
     */
    if ((error = xfs_dir2_shrink_inode(args, db, dbp))) {
        ASSERT(error != ENOSPC);
        xfs_trans_brelse(tp, dbp);
        return error;
    }
    /*
     * Eliminate the last bests entry from the table.
     */
    bestsp = xfs_dir2_leaf_bests_p(ltp);
    be32_add_cpu(&ltp->bestcount, -1);
    memmove(&bestsp[1], &bestsp[0], be32_to_cpu(ltp->bestcount) * sizeof(*bestsp));
    xfs_dir2_leaf_log_tail(tp, lbp);
    xfs_dir2_leaf_log_bests(tp, lbp, 0, be32_to_cpu(ltp->bestcount) - 1);
    return 0;
}

static inline size_t
xfs_dir2_leaf_size(
    struct xfs_dir2_leaf_hdr    *hdr,
    int             counts)
{
    int         entries;

    entries = be16_to_cpu(hdr->count) - be16_to_cpu(hdr->stale);
    return sizeof(xfs_dir2_leaf_hdr_t) +
        entries * sizeof(xfs_dir2_leaf_entry_t) +
        counts * sizeof(xfs_dir2_data_off_t) +
        sizeof(xfs_dir2_leaf_tail_t);
}

/*
 * Convert node form directory to leaf form directory.
 * The root of the node form dir needs to already be a LEAFN block.
 * Just return if we can't do anything.
 */
int                     /* error */
xfs_dir2_node_to_leaf(
    xfs_da_state_t      *state)     /* directory operation state */
{
    xfs_da_args_t       *args;      /* operation arguments */
    xfs_inode_t     *dp;        /* incore directory inode */
    int         error;      /* error return code */
    struct xfs_buf      *fbp;       /* buffer for freespace block */
    xfs_fileoff_t       fo;     /* freespace file offset */
    xfs_dir2_free_t     *free;      /* freespace structure */
    struct xfs_buf      *lbp;       /* buffer for leaf block */
    xfs_dir2_leaf_tail_t    *ltp;       /* tail of leaf structure */
    xfs_dir2_leaf_t     *leaf;      /* leaf structure */
    xfs_mount_t     *mp;        /* filesystem mount point */
    int         rval;       /* successful free trim? */
    xfs_trans_t     *tp;        /* transaction pointer */

    /*
     * There's more than a leaf level in the btree, so there must
     * be multiple leafn blocks.  Give up.
     */
    if (state->path.active > 1)
        return 0;
    args = state->args;

    trace_xfs_dir2_node_to_leaf(args);

    mp = state->mp;
    dp = args->dp;
    tp = args->trans;
    /*
     * Get the last offset in the file.
     */
    if ((error = xfs_bmap_last_offset(tp, dp, &fo, XFS_DATA_FORK))) {
        return error;
    }
    fo -= mp->m_dirblkfsbs;
    /*
     * If there are freespace blocks other than the first one,
     * take this opportunity to remove trailing empty freespace blocks
     * that may have been left behind during no-space-reservation
     * operations.
     */
    while (fo > mp->m_dirfreeblk) {
        if ((error = xfs_dir2_node_trim_free(args, fo, &rval))) {
            return error;
        }
        if (rval)
            fo -= mp->m_dirblkfsbs;
        else
            return 0;
    }
    /*
     * Now find the block just before the freespace block.
     */
    if ((error = xfs_bmap_last_before(tp, dp, &fo, XFS_DATA_FORK))) {
        return error;
    }
    /*
     * If it's not the single leaf block, give up.
     */
    if (XFS_FSB_TO_B(mp, fo) > XFS_DIR2_LEAF_OFFSET + mp->m_dirblksize)
        return 0;
    lbp = state->path.blk[0].bp;
    leaf = lbp->b_addr;
    ASSERT(leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAFN_MAGIC));
    /*
     * Read the freespace block.
     */
    if ((error = xfs_da_read_buf(tp, dp, mp->m_dirfreeblk, -1, &fbp,
            XFS_DATA_FORK))) {
        return error;
    }
    free = fbp->b_addr;
    ASSERT(free->hdr.magic == cpu_to_be32(XFS_DIR2_FREE_MAGIC));
    ASSERT(!free->hdr.firstdb);

    /*
     * Now see if the leafn and free data will fit in a leaf1.
     * If not, release the buffer and give up.
     */
    if (xfs_dir2_leaf_size(&leaf->hdr, be32_to_cpu(free->hdr.nvalid)) >
            mp->m_dirblksize) {
        xfs_trans_brelse(tp, fbp);
        return 0;
    }

    /*
     * If the leaf has any stale entries in it, compress them out.
     * The compact routine will log the header.
     */
    if (be16_to_cpu(leaf->hdr.stale))
        xfs_dir2_leaf_compact(args, lbp);
    else
        xfs_dir2_leaf_log_header(tp, lbp);
    leaf->hdr.info.magic = cpu_to_be16(XFS_DIR2_LEAF1_MAGIC);
    /*
     * Set up the leaf tail from the freespace block.
     */
    ltp = xfs_dir2_leaf_tail_p(mp, leaf);
    ltp->bestcount = free->hdr.nvalid;
    /*
     * Set up the leaf bests table.
     */
    memcpy(xfs_dir2_leaf_bests_p(ltp), free->bests,
        be32_to_cpu(ltp->bestcount) * sizeof(xfs_dir2_data_off_t));
    xfs_dir2_leaf_log_bests(tp, lbp, 0, be32_to_cpu(ltp->bestcount) - 1);
    xfs_dir2_leaf_log_tail(tp, lbp);
    xfs_dir2_leaf_check(dp, lbp);
    /*
     * Get rid of the freespace block.
     */
    error = xfs_dir2_shrink_inode(args, XFS_DIR2_FREE_FIRSTDB(mp), fbp);
    if (error) {
        /*
         * This can't fail here because it can only happen when
         * punching out the middle of an extent, and this is an
         * isolated block.
         */
        ASSERT(error != ENOSPC);
        return error;
    }
    fbp = NULL;
    /*
     * Now see if we can convert the single-leaf directory
     * down to a block form directory.
     * This routine always kills the dabuf for the leaf, so
     * eliminate it from the path.
     */
    error = xfs_dir2_leaf_to_block(args, lbp, NULL);
    state->path.blk[0].bp = NULL;
    return error;
}