Merge branch 'x86/doc' into x86/core

[linux-2.6] / fs / xfs / xfs_dir2_leaf.c

/*
 * 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_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_da_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_attr_sf.h"
#include "xfs_dir2_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_bmap.h"
#include "xfs_dir2_data.h"
#include "xfs_dir2_leaf.h"
#include "xfs_dir2_block.h"
#include "xfs_dir2_node.h"
#include "xfs_dir2_trace.h"
#include "xfs_error.h"

/*
 * Local function declarations.
 */
#ifdef DEBUG
static void xfs_dir2_leaf_check(xfs_inode_t *dp, xfs_dabuf_t *bp);
#else
#define xfs_dir2_leaf_check(dp, bp)
#endif
static int xfs_dir2_leaf_lookup_int(xfs_da_args_t *args, xfs_dabuf_t **lbpp,
                                    int *indexp, xfs_dabuf_t **dbpp);
static void xfs_dir2_leaf_log_bests(struct xfs_trans *tp, struct xfs_dabuf *bp,
                                    int first, int last);
static void xfs_dir2_leaf_log_tail(struct xfs_trans *tp, struct xfs_dabuf *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 */
        xfs_dabuf_t             *dbp)           /* input block's buffer */
{
        __be16                  *bestsp;        /* leaf's bestsp entries */
        xfs_dablk_t             blkno;          /* leaf block's bno */
        xfs_dir2_block_t        *block;         /* block structure */
        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 */
        xfs_dabuf_t             *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 */

        xfs_dir2_trace_args_b("block_to_leaf", args, dbp);
        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->data;
        block = dbp->data;
        xfs_dir2_data_check(dp, dbp);
        btp = xfs_dir2_block_tail_p(mp, block);
        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 *)block),
                (xfs_dir2_data_aoff_t)((char *)block + mp->m_dirblksize -
                                       (char *)blp),
                &needlog, &needscan);
        /*
         * Fix up the block header, make it a data block.
         */
        block->hdr.magic = cpu_to_be32(XFS_DIR2_DATA_MAGIC);
        if (needscan)
                xfs_dir2_data_freescan(mp, (xfs_dir2_data_t *)block, &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] =  block->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);
        xfs_da_buf_done(lbp);
        return 0;
}

/*
 * 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_t         *data;          /* data block structure */
        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_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 */
        xfs_dabuf_t             *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 */

        xfs_dir2_trace_args("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->data;
        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(be16_to_cpu(bestsp[i]) != 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 (be16_to_cpu(bestsp[i]) == 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 =
                (leaf->hdr.stale ? 0 : (uint)sizeof(leaf->ents[0])) +
                (use_block != -1 ? 0 : (uint)sizeof(leaf->bests[0]));
        /*
         * 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 && be16_to_cpu(bestsp[use_block]) == 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_da_brelse(tp, lbp);
                        return XFS_ERROR(ENOSPC);
                }
                /*
                 * Convert to node form.
                 */
                error = xfs_dir2_leaf_to_node(args, lbp);
                xfs_da_buf_done(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_da_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_da_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_da_brelse(tp, lbp);
                        return error;
                }
                /*
                 * Initialize the block.
                 */
                if ((error = xfs_dir2_data_init(args, use_block, &dbp))) {
                        xfs_da_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);
                data = dbp->data;
                bestsp[use_block] = data->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_da_brelse(tp, lbp);
                        return error;
                }
                data = dbp->data;
                grown = 0;
        }
        xfs_dir2_data_check(dp, dbp);
        /*
         * Point to the biggest freespace in our data block.
         */
        dup = (xfs_dir2_data_unused_t *)
              ((char *)data + be16_to_cpu(data->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 *)data), 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 *)data);
        /*
         * Need to scan fix up the bestfree table.
         */
        if (needscan)
                xfs_dir2_data_freescan(mp, data, &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(data->hdr.bestfree[0].length)) {
                bestsp[use_block] = data->hdr.bestfree[0].length;
                if (!grown)
                        xfs_dir2_leaf_log_bests(tp, lbp, use_block, use_block);
        }
        /*
         * Now we need to make room to insert the leaf entry.
         * If there are no stale entries, we just insert a hole at index.
         */
        if (!leaf->hdr.stale) {
                /*
                 * lep is still good as the index leaf entry.
                 */
                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);
        }
        /*
         * 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.
         */
        else {
                /*
                 * If we didn't compact before, we need to find the nearest
                 * stale entries before and after our insertion point.
                 */
                if (compact == 0) {
                        /*
                         * Find the first stale entry before the insertion
                         * point, if any.
                         */
                        for (lowstale = index - 1;
                             lowstale >= 0 &&
                                be32_to_cpu(leaf->ents[lowstale].address) !=
                                XFS_DIR2_NULL_DATAPTR;
                             lowstale--)
                                continue;
                        /*
                         * Find the next stale entry at or after the insertion
                         * point, if any.   Stop if we go so far that the
                         * lowstale entry would be better.
                         */
                        for (highstale = index;
                             highstale < be16_to_cpu(leaf->hdr.count) &&
                                be32_to_cpu(leaf->ents[highstale].address) !=
                                XFS_DIR2_NULL_DATAPTR &&
                                (lowstale < 0 ||
                                 index - lowstale - 1 >= highstale - index);
                             highstale++)
                                continue;
                }
                /*
                 * 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(be32_to_cpu(leaf->ents[lowstale].address) ==
                               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(*lep));
                        lep = &leaf->ents[index - 1];
                        lfloglow = MIN(lowstale, lfloglow);
                        lfloghigh = MAX(index - 1, lfloghigh);
                }
                /*
                 * The high one is better, so use that one.
                 */
                else {
                        ASSERT(highstale - index >= 0);
                        ASSERT(be32_to_cpu(leaf->ents[highstale].address) ==
                               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(*lep));
                        lep = &leaf->ents[index];
                        lfloglow = MIN(index, lfloglow);
                        lfloghigh = MAX(highstale, lfloghigh);
                }
                be16_add_cpu(&leaf->hdr.stale, -1);
        }
        /*
         * 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_da_buf_done(lbp);
        xfs_dir2_data_check(dp, dbp);
        xfs_da_buf_done(dbp);
        return 0;
}

#ifdef DEBUG
/*
 * Check the internal consistency of a leaf1 block.
 * Pop an assert if something is wrong.
 */
void
xfs_dir2_leaf_check(
        xfs_inode_t             *dp,            /* incore directory inode */
        xfs_dabuf_t             *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->data;
        mp = dp->i_mount;
        ASSERT(be16_to_cpu(leaf->hdr.info.magic) == 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 (be32_to_cpu(leaf->ents[i].address) == 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 */
        xfs_dabuf_t     *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->data;
        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 (be32_to_cpu(leaf->ents[from].address) == 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(
        xfs_dabuf_t     *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->data;
        ASSERT(be16_to_cpu(leaf->hdr.stale) > 1);
        index = *indexp;
        /*
         * Find the first stale entry before our index, if any.
         */
        for (lowstale = index - 1;
             lowstale >= 0 &&
                be32_to_cpu(leaf->ents[lowstale].address) != XFS_DIR2_NULL_DATAPTR;
             lowstale--)
                continue;
        /*
         * Find the first stale entry at or after our index, if any.
         * Stop if the answer would be worse than lowstale.
         */
        for (highstale = index;
             highstale < be16_to_cpu(leaf->hdr.count) &&
                be32_to_cpu(leaf->ents[highstale].address) != XFS_DIR2_NULL_DATAPTR &&
                (lowstale < 0 || index - lowstale > highstale - index);
             highstale++)
                continue;
        /*
         * 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 &&
                    be32_to_cpu(leaf->ents[from].address) == 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;
}

/*
 * 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)
{
        xfs_dabuf_t             *bp;            /* data block buffer */
        int                     byteoff;        /* offset in current block */
        xfs_dir2_db_t           curdb;          /* db for current block */
        xfs_dir2_off_t          curoff;         /* current overall offset */
        xfs_dir2_data_t         *data;          /* data block structure */
        xfs_dir2_data_entry_t   *dep;           /* data entry */
        xfs_dir2_data_unused_t  *dup;           /* unused entry */
        int                     error = 0;      /* error return value */
        int                     i;              /* temporary loop index */
        int                     j;              /* temporary loop index */
        int                     length;         /* temporary length value */
        xfs_bmbt_irec_t         *map;           /* map vector for blocks */
        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 */
        xfs_mount_t             *mp;            /* filesystem mount point */
        xfs_dir2_off_t          newoff;         /* new curoff after new blk */
        int                     nmap;           /* mappings to ask xfs_bmapi */
        char                    *ptr = NULL;    /* pointer to current data */
        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 */
        xfs_ino_t               ino;

        /*
         * 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.
         */
        map_size = howmany(bufsize + mp->m_dirblksize, mp->m_sb.sb_blocksize);
        map = kmem_alloc(map_size * sizeof(*map), KM_SLEEP);
        map_valid = ra_index = ra_offset = ra_current = map_blocks = 0;
        bp = NULL;

        /*
         * 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_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->data + mp->m_dirblksize) {
                        /*
                         * If we have a buffer, we need to release it and
                         * take it out of the mapping.
                         */
                        if (bp) {
                                xfs_da_brelse(NULL, bp);
                                bp = NULL;
                                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((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 && --map_valid)
                                                memmove(&map[0], &map[1],
                                                        sizeof(map[0]) *
                                                        map_valid);
                                        i -= j;
                                }
                        }
                        /*
                         * Recalculate the readahead blocks wanted.
                         */
                        ra_want = howmany(bufsize + mp->m_dirblksize,
                                          mp->m_sb.sb_blocksize) - 1;

                        /*
                         * 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 + ra_want > map_blocks &&
                            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.
                                 */
                                nmap = map_size - map_valid;
                                error = xfs_bmapi(NULL, dp,
                                        map_off,
                                        xfs_dir2_byte_to_da(mp,
                                                XFS_DIR2_LEAF_OFFSET) - map_off,
                                        XFS_BMAPI_METADATA, NULL, 0,
                                        &map[map_valid], &nmap, NULL, NULL);
                                /*
                                 * 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)
                                        break;  /* 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 (nmap == map_size - map_valid)
                                        map_off =
                                        map[map_valid + nmap - 1].br_startoff +
                                        map[map_valid + nmap - 1].br_blockcount;
                                else
                                        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 = map_valid; i < map_valid + nmap; ) {
                                        if (map[i].br_startblock ==
                                            HOLESTARTBLOCK) {
                                                nmap--;
                                                length = map_valid + nmap - i;
                                                if (length)
                                                        memmove(&map[i],
                                                                &map[i + 1],
                                                                sizeof(map[i]) *
                                                                length);
                                        } else {
                                                map_blocks +=
                                                        map[i].br_blockcount;
                                                i++;
                                        }
                                }
                                map_valid += nmap;
                        }
                        /*
                         * No valid mappings, so no more data blocks.
                         */
                        if (!map_valid) {
                                curoff = xfs_dir2_da_to_byte(mp, map_off);
                                break;
                        }
                        /*
                         * Read the directory block starting at the first
                         * mapping.
                         */
                        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)
                                break;  /* XXX */
                        /*
                         * Adjust the current amount of read-ahead: we just
                         * read a block that was previously ra.
                         */
                        if (ra_current)
                                ra_current -= mp->m_dirblkfsbs;
                        /*
                         * Do we need more readahead?
                         */
                        for (ra_index = ra_offset = i = 0;
                             ra_want > ra_current && i < map_blocks;
                             i += mp->m_dirblkfsbs) {
                                ASSERT(ra_index < map_valid);
                                /*
                                 * Read-ahead a contiguous directory block.
                                 */
                                if (i > ra_current &&
                                    map[ra_index].br_blockcount >=
                                    mp->m_dirblkfsbs) {
                                        xfs_baread(mp->m_ddev_targp,
                                                XFS_FSB_TO_DADDR(mp,
                                                   map[ra_index].br_startblock +
                                                   ra_offset),
                                                (int)BTOBB(mp->m_dirblksize));
                                        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 > ra_current) {
                                        (void)xfs_da_reada_buf(NULL, dp,
                                                map[ra_index].br_startoff +
                                                ra_offset, XFS_DATA_FORK);
                                        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(mp->m_dirblkfsbs,
                                                (int)(map[ra_index].br_blockcount -
                                                ra_offset));
                                        j += length;
                                        ra_offset += length;
                                        /*
                                         * Advance to the next mapping if
                                         * this one is used up.
                                         */
                                        if (ra_offset ==
                                            map[ra_index].br_blockcount) {
                                                ra_offset = 0;
                                                ra_index++;
                                        }
                                }
                        }
                        /*
                         * Having done a read, we need to set a new offset.
                         */
                        newoff = xfs_dir2_db_off_to_byte(mp, 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) ==
                                       curdb);
                        data = bp->data;
                        xfs_dir2_data_check(dp, bp);
                        /*
                         * Find our position in the block.
                         */
                        ptr = (char *)&data->u;
                        byteoff = xfs_dir2_byte_to_off(mp, curoff);
                        /*
                         * Skip past the header.
                         */
                        if (byteoff == 0)
                                curoff += (uint)sizeof(data->hdr);
                        /*
                         * Skip past entries until we reach our offset.
                         */
                        else {
                                while ((char *)ptr - (char *)data < 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 *)data);
                                if (ptr >= (char *)data + 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;
                }

                /*
                 * Copy the entry into the putargs, and try formatting it.
                 */
                dep = (xfs_dir2_data_entry_t *)ptr;

                length = xfs_dir2_data_entsize(dep->namelen);

                ino = be64_to_cpu(dep->inumber);
#if XFS_BIG_INUMS
                ino += mp->m_inoadd;
#endif

                /*
                 * Won't fit.  Return to caller.
                 */
                if (filldir(dirent, dep->name, dep->namelen,
                            xfs_dir2_byte_to_dataptr(mp, curoff) & 0x7fffffff,
                            ino, DT_UNKNOWN))
                        break;

                /*
                 * Advance to next entry in the block.
                 */
                ptr += length;
                curoff += length;
                bufsize -= length;
        }

        /*
         * 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);
        if (bp)
                xfs_da_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 */
        xfs_dabuf_t             **bpp,          /* out: leaf buffer */
        int                     magic)          /* magic number for block */
{
        xfs_dabuf_t             *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->data;
        /*
         * 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 */
        xfs_dabuf_t             *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->data;
        ASSERT(be16_to_cpu(leaf->hdr.info.magic) == 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_da_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 */
        xfs_dabuf_t             *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->data;
        ASSERT(be16_to_cpu(leaf->hdr.info.magic) == XFS_DIR2_LEAF1_MAGIC ||
               be16_to_cpu(leaf->hdr.info.magic) == XFS_DIR2_LEAFN_MAGIC);
        firstlep = &leaf->ents[first];
        lastlep = &leaf->ents[last];
        xfs_da_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(
        xfs_trans_t             *tp,            /* transaction pointer */
        xfs_dabuf_t             *bp)            /* leaf buffer */
{
        xfs_dir2_leaf_t         *leaf;          /* leaf structure */

        leaf = bp->data;
        ASSERT(be16_to_cpu(leaf->hdr.info.magic) == XFS_DIR2_LEAF1_MAGIC ||
               be16_to_cpu(leaf->hdr.info.magic) == XFS_DIR2_LEAFN_MAGIC);
        xfs_da_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(
        xfs_trans_t             *tp,            /* transaction pointer */
        xfs_dabuf_t             *bp)            /* leaf buffer */
{
        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->data;
        ASSERT(be16_to_cpu(leaf->hdr.info.magic) == XFS_DIR2_LEAF1_MAGIC);
        ltp = xfs_dir2_leaf_tail_p(mp, leaf);
        xfs_da_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 */
{
        xfs_dabuf_t             *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 */
        xfs_dabuf_t             *lbp;           /* leaf buffer */
        xfs_dir2_leaf_t         *leaf;          /* leaf structure */
        xfs_dir2_leaf_entry_t   *lep;           /* leaf entry */
        xfs_trans_t             *tp;            /* transaction pointer */

        xfs_dir2_trace_args("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->data;
        /*
         * 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->data +
               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_da_brelse(tp, dbp);
        xfs_da_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 */
        xfs_dabuf_t             **lbpp,         /* out: leaf buffer */
        int                     *indexp,        /* out: index in leaf block */
        xfs_dabuf_t             **dbpp)         /* out: data buffer */
{
        xfs_dir2_db_t           curdb = -1;     /* current data block number */
        xfs_dabuf_t             *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 */
        xfs_dabuf_t             *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->data;
        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_da_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_da_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->data +
                        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_da_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_da_brelse(tp, lbp);
                                return error;
                        }
                }
                *dbpp = dbp;
                return 0;
        }
        /*
         * No match found, return ENOENT.
         */
        ASSERT(cidb == -1);
        if (dbp)
                xfs_da_brelse(tp, dbp);
        xfs_da_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_t         *data;          /* data block structure */
        xfs_dir2_db_t           db;             /* data block number */
        xfs_dabuf_t             *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 */
        xfs_dabuf_t             *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 */

        xfs_dir2_trace_args("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->data;
        data = dbp->data;
        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 *)data + xfs_dir2_dataptr_to_off(mp, be32_to_cpu(lep->address)));
        needscan = needlog = 0;
        oldbest = be16_to_cpu(data->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 *)data),
                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, data, &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(data->hdr.bestfree[0].length) != oldbest) {
                bestsp[db] = data->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(data->hdr.bestfree[0].length) ==
            mp->m_dirblksize - (uint)sizeof(data->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) {
                                xfs_da_buf_done(dbp);
                                error = 0;
                        }
                        xfs_dir2_leaf_check(dp, lbp);
                        xfs_da_buf_done(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 (be16_to_cpu(bestsp[i]) != 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_da_buf_done(dbp);
                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 */
{
        xfs_dabuf_t             *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 */
        xfs_dabuf_t             *lbp;           /* leaf buffer */
        xfs_dir2_leaf_t         *leaf;          /* leaf structure */
        xfs_dir2_leaf_entry_t   *lep;           /* leaf entry */
        xfs_trans_t             *tp;            /* transaction pointer */

        xfs_dir2_trace_args("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->data;
        /*
         * 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->data +
               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_da_buf_done(dbp);
        xfs_dir2_leaf_check(dp, lbp);
        xfs_da_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 */
        xfs_dabuf_t             *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->data;
#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 */
        xfs_dabuf_t             *lbp,           /* leaf buffer */
        xfs_dir2_db_t           db)             /* data block number */
{
        __be16                  *bestsp;        /* leaf bests table */
#ifdef DEBUG
        xfs_dir2_data_t         *data;          /* data block structure */
#endif
        xfs_dabuf_t             *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;
        }
#ifdef DEBUG
        data = dbp->data;
        ASSERT(be32_to_cpu(data->hdr.magic) == XFS_DIR2_DATA_MAGIC);
#endif
        /* this seems to be an error
         * data is only valid if DEBUG is defined?
         * RMC 09/08/1999
         */

        leaf = lbp->data;
        ltp = xfs_dir2_leaf_tail_p(mp, leaf);
        ASSERT(be16_to_cpu(data->hdr.bestfree[0].length) ==
               mp->m_dirblksize - (uint)sizeof(data->hdr));
        ASSERT(db == be32_to_cpu(ltp->bestcount) - 1);
        /*
         * Get rid of the data block.
         */
        if ((error = xfs_dir2_shrink_inode(args, db, dbp))) {
                ASSERT(error != ENOSPC);
                xfs_da_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;
}

/*
 * 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 */
        xfs_dabuf_t             *fbp;           /* buffer for freespace block */
        xfs_fileoff_t           fo;             /* freespace file offset */
        xfs_dir2_free_t         *free;          /* freespace structure */
        xfs_dabuf_t             *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;
        xfs_dir2_trace_args("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->data;
        ASSERT(be16_to_cpu(leaf->hdr.info.magic) == 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->data;
        ASSERT(be32_to_cpu(free->hdr.magic) == 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 ((uint)sizeof(leaf->hdr) +
            (be16_to_cpu(leaf->hdr.count) - be16_to_cpu(leaf->hdr.stale)) * (uint)sizeof(leaf->ents[0]) +
            be32_to_cpu(free->hdr.nvalid) * (uint)sizeof(leaf->bests[0]) +
            (uint)sizeof(leaf->tail) >
            mp->m_dirblksize) {
                xfs_da_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(leaf->bests[0]));
        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;
}