xfs_dir2_block.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_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_inode_item.h"
#include "xfs_dir2.h"
#include "xfs_dir2_format.h"
#include "xfs_dir2_priv.h"
#include "xfs_error.h"
#include "xfs_trace.h"

/*
 * Local function prototypes.
 */
static void xfs_dir2_block_log_leaf(xfs_trans_t *tp, struct xfs_buf *bp,
                    int first, int last);
static void xfs_dir2_block_log_tail(xfs_trans_t *tp, struct xfs_buf *bp);
static int xfs_dir2_block_lookup_int(xfs_da_args_t *args, struct xfs_buf **bpp,
                     int *entno);
static int xfs_dir2_block_sort(const void *a, const void *b);

static xfs_dahash_t xfs_dir_hash_dot, xfs_dir_hash_dotdot;

/*
 * One-time startup routine called from xfs_init().
 */
void
xfs_dir_startup(void)
{
    xfs_dir_hash_dot = xfs_da_hashname((unsigned char *)".", 1);
    xfs_dir_hash_dotdot = xfs_da_hashname((unsigned char *)"..", 2);
}

/*
 * Add an entry to a block directory.
 */
int                     /* error */
xfs_dir2_block_addname(
    xfs_da_args_t       *args)      /* directory op arguments */
{
    xfs_dir2_data_free_t    *bf;        /* bestfree table in block */
    xfs_dir2_data_hdr_t *hdr;       /* block header */
    xfs_dir2_leaf_entry_t   *blp;       /* block leaf entries */
    struct xfs_buf      *bp;        /* buffer for block */
    xfs_dir2_block_tail_t   *btp;       /* block tail */
    int         compact;    /* need to compact leaf ents */
    xfs_dir2_data_entry_t   *dep;       /* block data entry */
    xfs_inode_t     *dp;        /* directory inode */
    xfs_dir2_data_unused_t  *dup;       /* block unused entry */
    int         error;      /* error return value */
    xfs_dir2_data_unused_t  *enddup=NULL;   /* unused at end of data */
    xfs_dahash_t        hash;       /* hash value of found entry */
    int         high;       /* high index for binary srch */
    int         highstale;  /* high stale index */
    int         lfloghigh=0;    /* last final leaf to log */
    int         lfloglow=0; /* first final leaf to log */
    int         len;        /* length of the new entry */
    int         low;        /* low index for binary srch */
    int         lowstale;   /* low stale index */
    int         mid=0;      /* midpoint for binary srch */
    xfs_mount_t     *mp;        /* filesystem mount point */
    int         needlog;    /* need to log header */
    int         needscan;   /* need to rescan freespace */
    __be16          *tagp;      /* pointer to tag value */
    xfs_trans_t     *tp;        /* transaction structure */

    trace_xfs_dir2_block_addname(args);

    dp = args->dp;
    tp = args->trans;
    mp = dp->i_mount;
    /*
     * Read the (one and only) directory block into dabuf bp.
     */
    if ((error =
        xfs_da_read_buf(tp, dp, mp->m_dirdatablk, -1, &bp, XFS_DATA_FORK))) {
        return error;
    }
    ASSERT(bp != NULL);
    hdr = bp->b_addr;
    /*
     * Check the magic number, corrupted if wrong.
     */
    if (unlikely(hdr->magic != cpu_to_be32(XFS_DIR2_BLOCK_MAGIC))) {
        XFS_CORRUPTION_ERROR("xfs_dir2_block_addname",
                     XFS_ERRLEVEL_LOW, mp, hdr);
        xfs_trans_brelse(tp, bp);
        return XFS_ERROR(EFSCORRUPTED);
    }
    len = xfs_dir2_data_entsize(args->namelen);
    /*
     * Set up pointers to parts of the block.
     */
    bf = hdr->bestfree;
    btp = xfs_dir2_block_tail_p(mp, hdr);
    blp = xfs_dir2_block_leaf_p(btp);
    /*
     * No stale entries?  Need space for entry and new leaf.
     */
    if (!btp->stale) {
        /*
         * Tag just before the first leaf entry.
         */
        tagp = (__be16 *)blp - 1;
        /*
         * Data object just before the first leaf entry.
         */
        enddup = (xfs_dir2_data_unused_t *)((char *)hdr + be16_to_cpu(*tagp));
        /*
         * If it's not free then can't do this add without cleaning up:
         * the space before the first leaf entry needs to be free so it
         * can be expanded to hold the pointer to the new entry.
         */
        if (be16_to_cpu(enddup->freetag) != XFS_DIR2_DATA_FREE_TAG)
            dup = enddup = NULL;
        /*
         * Check out the biggest freespace and see if it's the same one.
         */
        else {
            dup = (xfs_dir2_data_unused_t *)
                  ((char *)hdr + be16_to_cpu(bf[0].offset));
            if (dup == enddup) {
                /*
                 * It is the biggest freespace, is it too small
                 * to hold the new leaf too?
                 */
                if (be16_to_cpu(dup->length) < len + (uint)sizeof(*blp)) {
                    /*
                     * Yes, we use the second-largest
                     * entry instead if it works.
                     */
                    if (be16_to_cpu(bf[1].length) >= len)
                        dup = (xfs_dir2_data_unused_t *)
                              ((char *)hdr +
                               be16_to_cpu(bf[1].offset));
                    else
                        dup = NULL;
                }
            } else {
                /*
                 * Not the same free entry,
                 * just check its length.
                 */
                if (be16_to_cpu(dup->length) < len) {
                    dup = NULL;
                }
            }
        }
        compact = 0;
    }
    /*
     * If there are stale entries we'll use one for the leaf.
     * Is the biggest entry enough to avoid compaction?
     */
    else if (be16_to_cpu(bf[0].length) >= len) {
        dup = (xfs_dir2_data_unused_t *)
              ((char *)hdr + be16_to_cpu(bf[0].offset));
        compact = 0;
    }
    /*
     * Will need to compact to make this work.
     */
    else {
        /*
         * Tag just before the first leaf entry.
         */
        tagp = (__be16 *)blp - 1;
        /*
         * Data object just before the first leaf entry.
         */
        dup = (xfs_dir2_data_unused_t *)((char *)hdr + be16_to_cpu(*tagp));
        /*
         * If it's not free then the data will go where the
         * leaf data starts now, if it works at all.
         */
        if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
            if (be16_to_cpu(dup->length) + (be32_to_cpu(btp->stale) - 1) *
                (uint)sizeof(*blp) < len)
                dup = NULL;
        } else if ((be32_to_cpu(btp->stale) - 1) * (uint)sizeof(*blp) < len)
            dup = NULL;
        else
            dup = (xfs_dir2_data_unused_t *)blp;
        compact = 1;
    }
    /*
     * If this isn't a real add, we're done with the buffer.
     */
    if (args->op_flags & XFS_DA_OP_JUSTCHECK)
        xfs_trans_brelse(tp, bp);
    /*
     * If we don't have space for the new entry & leaf ...
     */
    if (!dup) {
        /*
         * Not trying to actually do anything, or don't have
         * a space reservation: return no-space.
         */
        if ((args->op_flags & XFS_DA_OP_JUSTCHECK) || args->total == 0)
            return XFS_ERROR(ENOSPC);
        /*
         * Convert to the next larger format.
         * Then add the new entry in that format.
         */
        error = xfs_dir2_block_to_leaf(args, bp);
        if (error)
            return error;
        return xfs_dir2_leaf_addname(args);
    }
    /*
     * Just checking, and it would work, so say so.
     */
    if (args->op_flags & XFS_DA_OP_JUSTCHECK)
        return 0;
    needlog = needscan = 0;
    /*
     * If need to compact the leaf entries, do it now.
     * Leave the highest-numbered stale entry stale.
     * XXX should be the one closest to mid but mid is not yet computed.
     */
    if (compact) {
        int fromidx;        /* source leaf index */
        int toidx;          /* target leaf index */

        for (fromidx = toidx = be32_to_cpu(btp->count) - 1,
            highstale = lfloghigh = -1;
             fromidx >= 0;
             fromidx--) {
            if (blp[fromidx].address ==
                cpu_to_be32(XFS_DIR2_NULL_DATAPTR)) {
                if (highstale == -1)
                    highstale = toidx;
                else {
                    if (lfloghigh == -1)
                        lfloghigh = toidx;
                    continue;
                }
            }
            if (fromidx < toidx)
                blp[toidx] = blp[fromidx];
            toidx--;
        }
        lfloglow = toidx + 1 - (be32_to_cpu(btp->stale) - 1);
        lfloghigh -= be32_to_cpu(btp->stale) - 1;
        be32_add_cpu(&btp->count, -(be32_to_cpu(btp->stale) - 1));
        xfs_dir2_data_make_free(tp, bp,
            (xfs_dir2_data_aoff_t)((char *)blp - (char *)hdr),
            (xfs_dir2_data_aoff_t)((be32_to_cpu(btp->stale) - 1) * sizeof(*blp)),
            &needlog, &needscan);
        blp += be32_to_cpu(btp->stale) - 1;
        btp->stale = cpu_to_be32(1);
        /*
         * If we now need to rebuild the bestfree map, do so.
         * This needs to happen before the next call to use_free.
         */
        if (needscan) {
            xfs_dir2_data_freescan(mp, hdr, &needlog);
            needscan = 0;
        }
    }
    /*
     * Set leaf logging boundaries to impossible state.
     * For the no-stale case they're set explicitly.
     */
    else if (btp->stale) {
        lfloglow = be32_to_cpu(btp->count);
        lfloghigh = -1;
    }
    /*
     * Find the slot that's first lower than our hash value, -1 if none.
     */
    for (low = 0, high = be32_to_cpu(btp->count) - 1; low <= high; ) {
        mid = (low + high) >> 1;
        if ((hash = be32_to_cpu(blp[mid].hashval)) == args->hashval)
            break;
        if (hash < args->hashval)
            low = mid + 1;
        else
            high = mid - 1;
    }
    while (mid >= 0 && be32_to_cpu(blp[mid].hashval) >= args->hashval) {
        mid--;
    }
    /*
     * No stale entries, will use enddup space to hold new leaf.
     */
    if (!btp->stale) {
        /*
         * Mark the space needed for the new leaf entry, now in use.
         */
        xfs_dir2_data_use_free(tp, bp, enddup,
            (xfs_dir2_data_aoff_t)
            ((char *)enddup - (char *)hdr + be16_to_cpu(enddup->length) -
             sizeof(*blp)),
            (xfs_dir2_data_aoff_t)sizeof(*blp),
            &needlog, &needscan);
        /*
         * Update the tail (entry count).
         */
        be32_add_cpu(&btp->count, 1);
        /*
         * If we now need to rebuild the bestfree map, do so.
         * This needs to happen before the next call to use_free.
         */
        if (needscan) {
            xfs_dir2_data_freescan(mp, hdr, &needlog);
            needscan = 0;
        }
        /*
         * Adjust pointer to the first leaf entry, we're about to move
         * the table up one to open up space for the new leaf entry.
         * Then adjust our index to match.
         */
        blp--;
        mid++;
        if (mid)
            memmove(blp, &blp[1], mid * sizeof(*blp));
        lfloglow = 0;
        lfloghigh = mid;
    }
    /*
     * Use a stale leaf for our new entry.
     */
    else {
        for (lowstale = mid;
             lowstale >= 0 &&
            blp[lowstale].address !=
            cpu_to_be32(XFS_DIR2_NULL_DATAPTR);
             lowstale--)
            continue;
        for (highstale = mid + 1;
             highstale < be32_to_cpu(btp->count) &&
            blp[highstale].address !=
            cpu_to_be32(XFS_DIR2_NULL_DATAPTR) &&
            (lowstale < 0 || mid - lowstale > highstale - mid);
             highstale++)
            continue;
        /*
         * Move entries toward the low-numbered stale entry.
         */
        if (lowstale >= 0 &&
            (highstale == be32_to_cpu(btp->count) ||
             mid - lowstale <= highstale - mid)) {
            if (mid - lowstale)
                memmove(&blp[lowstale], &blp[lowstale + 1],
                    (mid - lowstale) * sizeof(*blp));
            lfloglow = MIN(lowstale, lfloglow);
            lfloghigh = MAX(mid, lfloghigh);
        }
        /*
         * Move entries toward the high-numbered stale entry.
         */
        else {
            ASSERT(highstale < be32_to_cpu(btp->count));
            mid++;
            if (highstale - mid)
                memmove(&blp[mid + 1], &blp[mid],
                    (highstale - mid) * sizeof(*blp));
            lfloglow = MIN(mid, lfloglow);
            lfloghigh = MAX(highstale, lfloghigh);
        }
        be32_add_cpu(&btp->stale, -1);
    }
    /*
     * Point to the new data entry.
     */
    dep = (xfs_dir2_data_entry_t *)dup;
    /*
     * Fill in the leaf entry.
     */
    blp[mid].hashval = cpu_to_be32(args->hashval);
    blp[mid].address = cpu_to_be32(xfs_dir2_byte_to_dataptr(mp,
                (char *)dep - (char *)hdr));
    xfs_dir2_block_log_leaf(tp, bp, lfloglow, lfloghigh);
    /*
     * Mark space for the data entry used.
     */
    xfs_dir2_data_use_free(tp, bp, dup,
        (xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr),
        (xfs_dir2_data_aoff_t)len, &needlog, &needscan);
    /*
     * Create the new data entry.
     */
    dep->inumber = cpu_to_be64(args->inumber);
    dep->namelen = args->namelen;
    memcpy(dep->name, args->name, args->namelen);
    tagp = xfs_dir2_data_entry_tag_p(dep);
    *tagp = cpu_to_be16((char *)dep - (char *)hdr);
    /*
     * Clean up the bestfree array and log the header, tail, and entry.
     */
    if (needscan)
        xfs_dir2_data_freescan(mp, hdr, &needlog);
    if (needlog)
        xfs_dir2_data_log_header(tp, bp);
    xfs_dir2_block_log_tail(tp, bp);
    xfs_dir2_data_log_entry(tp, bp, dep);
    xfs_dir2_data_check(dp, bp);
    return 0;
}

/*
 * Readdir for block directories.
 */
int                     /* error */
xfs_dir2_block_getdents(
    xfs_inode_t     *dp,        /* incore inode */
    void            *dirent,
    xfs_off_t       *offset,
    filldir_t       filldir)
{
    xfs_dir2_data_hdr_t *hdr;       /* block header */
    struct xfs_buf      *bp;        /* buffer for block */
    xfs_dir2_block_tail_t   *btp;       /* block tail */
    xfs_dir2_data_entry_t   *dep;       /* block data entry */
    xfs_dir2_data_unused_t  *dup;       /* block unused entry */
    char            *endptr;    /* end of the data entries */
    int         error;      /* error return value */
    xfs_mount_t     *mp;        /* filesystem mount point */
    char            *ptr;       /* current data entry */
    int         wantoff;    /* starting block offset */
    xfs_off_t       cook;

    mp = dp->i_mount;
    /*
     * If the block number in the offset is out of range, we're done.
     */
    if (xfs_dir2_dataptr_to_db(mp, *offset) > mp->m_dirdatablk) {
        return 0;
    }
    /*
     * Can't read the block, give up, else get dabuf in bp.
     */
    error = xfs_da_read_buf(NULL, dp, mp->m_dirdatablk, -1,
                &bp, XFS_DATA_FORK);
    if (error)
        return error;

    ASSERT(bp != NULL);
    /*
     * Extract the byte offset we start at from the seek pointer.
     * We'll skip entries before this.
     */
    wantoff = xfs_dir2_dataptr_to_off(mp, *offset);
    hdr = bp->b_addr;
    xfs_dir2_data_check(dp, bp);
    /*
     * Set up values for the loop.
     */
    btp = xfs_dir2_block_tail_p(mp, hdr);
    ptr = (char *)(hdr + 1);
    endptr = (char *)xfs_dir2_block_leaf_p(btp);

    /*
     * Loop over the data portion of the block.
     * Each object is a real entry (dep) or an unused one (dup).
     */
    while (ptr < endptr) {
        dup = (xfs_dir2_data_unused_t *)ptr;
        /*
         * Unused, skip it.
         */
        if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
            ptr += be16_to_cpu(dup->length);
            continue;
        }

        dep = (xfs_dir2_data_entry_t *)ptr;

        /*
         * Bump pointer for the next iteration.
         */
        ptr += xfs_dir2_data_entsize(dep->namelen);
        /*
         * The entry is before the desired starting point, skip it.
         */
        if ((char *)dep - (char *)hdr < wantoff)
            continue;

        cook = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk,
                        (char *)dep - (char *)hdr);

        /*
         * If it didn't fit, set the final offset to here & return.
         */
        if (filldir(dirent, (char *)dep->name, dep->namelen,
                cook & 0x7fffffff, be64_to_cpu(dep->inumber),
                DT_UNKNOWN)) {
            *offset = cook & 0x7fffffff;
            xfs_trans_brelse(NULL, bp);
            return 0;
        }
    }

    /*
     * Reached the end of the block.
     * Set the offset to a non-existent block 1 and return.
     */
    *offset = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk + 1, 0) &
            0x7fffffff;
    xfs_trans_brelse(NULL, bp);
    return 0;
}

/*
 * Log leaf entries from the block.
 */
static void
xfs_dir2_block_log_leaf(
    xfs_trans_t     *tp,        /* transaction structure */
    struct xfs_buf      *bp,        /* block buffer */
    int         first,      /* index of first logged leaf */
    int         last)       /* index of last logged leaf */
{
    xfs_dir2_data_hdr_t *hdr = bp->b_addr;
    xfs_dir2_leaf_entry_t   *blp;
    xfs_dir2_block_tail_t   *btp;

    btp = xfs_dir2_block_tail_p(tp->t_mountp, hdr);
    blp = xfs_dir2_block_leaf_p(btp);
    xfs_trans_log_buf(tp, bp, (uint)((char *)&blp[first] - (char *)hdr),
        (uint)((char *)&blp[last + 1] - (char *)hdr - 1));
}

/*
 * Log the block tail.
 */
static void
xfs_dir2_block_log_tail(
    xfs_trans_t     *tp,        /* transaction structure */
    struct xfs_buf      *bp)        /* block buffer */
{
    xfs_dir2_data_hdr_t *hdr = bp->b_addr;
    xfs_dir2_block_tail_t   *btp;

    btp = xfs_dir2_block_tail_p(tp->t_mountp, hdr);
    xfs_trans_log_buf(tp, bp, (uint)((char *)btp - (char *)hdr),
        (uint)((char *)(btp + 1) - (char *)hdr - 1));
}

/*
 * Look up an entry in the block.  This is the external routine,
 * xfs_dir2_block_lookup_int does the real work.
 */
int                     /* error */
xfs_dir2_block_lookup(
    xfs_da_args_t       *args)      /* dir lookup arguments */
{
    xfs_dir2_data_hdr_t *hdr;       /* block header */
    xfs_dir2_leaf_entry_t   *blp;       /* block leaf entries */
    struct xfs_buf      *bp;        /* block buffer */
    xfs_dir2_block_tail_t   *btp;       /* block tail */
    xfs_dir2_data_entry_t   *dep;       /* block data entry */
    xfs_inode_t     *dp;        /* incore inode */
    int         ent;        /* entry index */
    int         error;      /* error return value */
    xfs_mount_t     *mp;        /* filesystem mount point */

    trace_xfs_dir2_block_lookup(args);

    /*
     * Get the buffer, look up the entry.
     * If not found (ENOENT) then return, have no buffer.
     */
    if ((error = xfs_dir2_block_lookup_int(args, &bp, &ent)))
        return error;
    dp = args->dp;
    mp = dp->i_mount;
    hdr = bp->b_addr;
    xfs_dir2_data_check(dp, bp);
    btp = xfs_dir2_block_tail_p(mp, hdr);
    blp = xfs_dir2_block_leaf_p(btp);
    /*
     * Get the offset from the leaf entry, to point to the data.
     */
    dep = (xfs_dir2_data_entry_t *)((char *)hdr +
        xfs_dir2_dataptr_to_off(mp, be32_to_cpu(blp[ent].address)));
    /*
     * Fill in inode number, CI name if appropriate, release the block.
     */
    args->inumber = be64_to_cpu(dep->inumber);
    error = xfs_dir_cilookup_result(args, dep->name, dep->namelen);
    xfs_trans_brelse(args->trans, bp);
    return XFS_ERROR(error);
}

/*
 * Internal block lookup routine.
 */
static int                  /* error */
xfs_dir2_block_lookup_int(
    xfs_da_args_t       *args,      /* dir lookup arguments */
    struct xfs_buf      **bpp,      /* returned block buffer */
    int         *entno)     /* returned entry number */
{
    xfs_dir2_dataptr_t  addr;       /* data entry address */
    xfs_dir2_data_hdr_t *hdr;       /* block header */
    xfs_dir2_leaf_entry_t   *blp;       /* block leaf entries */
    struct xfs_buf      *bp;        /* block buffer */
    xfs_dir2_block_tail_t   *btp;       /* block tail */
    xfs_dir2_data_entry_t   *dep;       /* block data entry */
    xfs_inode_t     *dp;        /* incore inode */
    int         error;      /* error return value */
    xfs_dahash_t        hash;       /* found hash value */
    int         high;       /* binary search high index */
    int         low;        /* binary search low index */
    int         mid;        /* binary search current idx */
    xfs_mount_t     *mp;        /* filesystem mount point */
    xfs_trans_t     *tp;        /* transaction pointer */
    enum xfs_dacmp      cmp;        /* comparison result */

    dp = args->dp;
    tp = args->trans;
    mp = dp->i_mount;
    /*
     * Read the buffer, return error if we can't get it.
     */
    if ((error =
        xfs_da_read_buf(tp, dp, mp->m_dirdatablk, -1, &bp, XFS_DATA_FORK))) {
        return error;
    }
    ASSERT(bp != NULL);
    hdr = bp->b_addr;
    xfs_dir2_data_check(dp, bp);
    btp = xfs_dir2_block_tail_p(mp, hdr);
    blp = xfs_dir2_block_leaf_p(btp);
    /*
     * Loop doing a binary search for our hash value.
     * Find our entry, ENOENT if it's not there.
     */
    for (low = 0, high = be32_to_cpu(btp->count) - 1; ; ) {
        ASSERT(low <= high);
        mid = (low + high) >> 1;
        if ((hash = be32_to_cpu(blp[mid].hashval)) == args->hashval)
            break;
        if (hash < args->hashval)
            low = mid + 1;
        else
            high = mid - 1;
        if (low > high) {
            ASSERT(args->op_flags & XFS_DA_OP_OKNOENT);
            xfs_trans_brelse(tp, bp);
            return XFS_ERROR(ENOENT);
        }
    }
    /*
     * Back up to the first one with the right hash value.
     */
    while (mid > 0 && be32_to_cpu(blp[mid - 1].hashval) == args->hashval) {
        mid--;
    }
    /*
     * Now loop forward through all the entries with the
     * right hash value looking for our name.
     */
    do {
        if ((addr = be32_to_cpu(blp[mid].address)) == XFS_DIR2_NULL_DATAPTR)
            continue;
        /*
         * Get pointer to the entry from the leaf.
         */
        dep = (xfs_dir2_data_entry_t *)
            ((char *)hdr + xfs_dir2_dataptr_to_off(mp, addr));
        /*
         * 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;
            *bpp = bp;
            *entno = mid;
            if (cmp == XFS_CMP_EXACT)
                return 0;
        }
    } while (++mid < be32_to_cpu(btp->count) &&
            be32_to_cpu(blp[mid].hashval) == hash);

    ASSERT(args->op_flags & XFS_DA_OP_OKNOENT);
    /*
     * Here, we can only be doing a lookup (not a rename or replace).
     * If a case-insensitive match was found earlier, return success.
     */
    if (args->cmpresult == XFS_CMP_CASE)
        return 0;
    /*
     * No match, release the buffer and return ENOENT.
     */
    xfs_trans_brelse(tp, bp);
    return XFS_ERROR(ENOENT);
}

/*
 * Remove an entry from a block format directory.
 * If that makes the block small enough to fit in shortform, transform it.
 */
int                     /* error */
xfs_dir2_block_removename(
    xfs_da_args_t       *args)      /* directory operation args */
{
    xfs_dir2_data_hdr_t *hdr;       /* block header */
    xfs_dir2_leaf_entry_t   *blp;       /* block leaf pointer */
    struct xfs_buf      *bp;        /* block buffer */
    xfs_dir2_block_tail_t   *btp;       /* block tail */
    xfs_dir2_data_entry_t   *dep;       /* block data entry */
    xfs_inode_t     *dp;        /* incore inode */
    int         ent;        /* block leaf entry index */
    int         error;      /* error return value */
    xfs_mount_t     *mp;        /* filesystem mount point */
    int         needlog;    /* need to log block header */
    int         needscan;   /* need to fixup bestfree */
    xfs_dir2_sf_hdr_t   sfh;        /* shortform header */
    int         size;       /* shortform size */
    xfs_trans_t     *tp;        /* transaction pointer */

    trace_xfs_dir2_block_removename(args);

    /*
     * Look up the entry in the block.  Gets the buffer and entry index.
     * It will always be there, the vnodeops level does a lookup first.
     */
    if ((error = xfs_dir2_block_lookup_int(args, &bp, &ent))) {
        return error;
    }
    dp = args->dp;
    tp = args->trans;
    mp = dp->i_mount;
    hdr = bp->b_addr;
    btp = xfs_dir2_block_tail_p(mp, hdr);
    blp = xfs_dir2_block_leaf_p(btp);
    /*
     * Point to the data entry using the leaf entry.
     */
    dep = (xfs_dir2_data_entry_t *)
          ((char *)hdr + xfs_dir2_dataptr_to_off(mp, be32_to_cpu(blp[ent].address)));
    /*
     * Mark the data entry's space free.
     */
    needlog = needscan = 0;
    xfs_dir2_data_make_free(tp, bp,
        (xfs_dir2_data_aoff_t)((char *)dep - (char *)hdr),
        xfs_dir2_data_entsize(dep->namelen), &needlog, &needscan);
    /*
     * Fix up the block tail.
     */
    be32_add_cpu(&btp->stale, 1);
    xfs_dir2_block_log_tail(tp, bp);
    /*
     * Remove the leaf entry by marking it stale.
     */
    blp[ent].address = cpu_to_be32(XFS_DIR2_NULL_DATAPTR);
    xfs_dir2_block_log_leaf(tp, bp, ent, ent);
    /*
     * Fix up bestfree, log the header if necessary.
     */
    if (needscan)
        xfs_dir2_data_freescan(mp, hdr, &needlog);
    if (needlog)
        xfs_dir2_data_log_header(tp, bp);
    xfs_dir2_data_check(dp, bp);
    /*
     * See if the size as a shortform is good enough.
     */
    size = xfs_dir2_block_sfsize(dp, hdr, &sfh);
    if (size > XFS_IFORK_DSIZE(dp))
        return 0;

    /*
     * If it works, do the conversion.
     */
    return xfs_dir2_block_to_sf(args, bp, size, &sfh);
}

/*
 * Replace an entry in a V2 block directory.
 * Change the inode number to the new value.
 */
int                     /* error */
xfs_dir2_block_replace(
    xfs_da_args_t       *args)      /* directory operation args */
{
    xfs_dir2_data_hdr_t *hdr;       /* block header */
    xfs_dir2_leaf_entry_t   *blp;       /* block leaf entries */
    struct xfs_buf      *bp;        /* block buffer */
    xfs_dir2_block_tail_t   *btp;       /* block tail */
    xfs_dir2_data_entry_t   *dep;       /* block data entry */
    xfs_inode_t     *dp;        /* incore inode */
    int         ent;        /* leaf entry index */
    int         error;      /* error return value */
    xfs_mount_t     *mp;        /* filesystem mount point */

    trace_xfs_dir2_block_replace(args);

    /*
     * Lookup the entry in the directory.  Get buffer and entry index.
     * This will always succeed since the caller has already done a lookup.
     */
    if ((error = xfs_dir2_block_lookup_int(args, &bp, &ent))) {
        return error;
    }
    dp = args->dp;
    mp = dp->i_mount;
    hdr = bp->b_addr;
    btp = xfs_dir2_block_tail_p(mp, hdr);
    blp = xfs_dir2_block_leaf_p(btp);
    /*
     * Point to the data entry we need to change.
     */
    dep = (xfs_dir2_data_entry_t *)
          ((char *)hdr + xfs_dir2_dataptr_to_off(mp, be32_to_cpu(blp[ent].address)));
    ASSERT(be64_to_cpu(dep->inumber) != args->inumber);
    /*
     * Change the inode number to the new value.
     */
    dep->inumber = cpu_to_be64(args->inumber);
    xfs_dir2_data_log_entry(args->trans, bp, dep);
    xfs_dir2_data_check(dp, bp);
    return 0;
}

/*
 * Qsort comparison routine for the block leaf entries.
 */
static int                  /* sort order */
xfs_dir2_block_sort(
    const void          *a, /* first leaf entry */
    const void          *b) /* second leaf entry */
{
    const xfs_dir2_leaf_entry_t *la;    /* first leaf entry */
    const xfs_dir2_leaf_entry_t *lb;    /* second leaf entry */

    la = a;
    lb = b;
    return be32_to_cpu(la->hashval) < be32_to_cpu(lb->hashval) ? -1 :
        (be32_to_cpu(la->hashval) > be32_to_cpu(lb->hashval) ? 1 : 0);
}

/*
 * Convert a V2 leaf directory to a V2 block directory if possible.
 */
int                     /* error */
xfs_dir2_leaf_to_block(
    xfs_da_args_t       *args,      /* operation arguments */
    struct xfs_buf      *lbp,       /* leaf buffer */
    struct xfs_buf      *dbp)       /* data buffer */
{
    __be16          *bestsp;    /* leaf bests table */
    xfs_dir2_data_hdr_t *hdr;       /* block header */
    xfs_dir2_block_tail_t   *btp;       /* block tail */
    xfs_inode_t     *dp;        /* incore directory inode */
    xfs_dir2_data_unused_t  *dup;       /* unused data entry */
    int         error;      /* error return value */
    int         from;       /* leaf from index */
    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;        /* file system mount point */
    int         needlog;    /* need to log data header */
    int         needscan;   /* need to scan for bestfree */
    xfs_dir2_sf_hdr_t   sfh;        /* shortform header */
    int         size;       /* bytes used */
    __be16          *tagp;      /* end of entry (tag) */
    int         to;     /* block/leaf to index */
    xfs_trans_t     *tp;        /* transaction pointer */

    trace_xfs_dir2_leaf_to_block(args);

    dp = args->dp;
    tp = args->trans;
    mp = dp->i_mount;
    leaf = lbp->b_addr;
    ASSERT(leaf->hdr.info.magic == cpu_to_be16(XFS_DIR2_LEAF1_MAGIC));
    ltp = xfs_dir2_leaf_tail_p(mp, leaf);
    /*
     * If there are data blocks other than the first one, take this
     * opportunity to remove trailing empty data blocks that may have
     * been left behind during no-space-reservation operations.
     * These will show up in the leaf bests table.
     */
    while (dp->i_d.di_size > mp->m_dirblksize) {
        bestsp = xfs_dir2_leaf_bests_p(ltp);
        if (be16_to_cpu(bestsp[be32_to_cpu(ltp->bestcount) - 1]) ==
            mp->m_dirblksize - (uint)sizeof(*hdr)) {
            if ((error =
                xfs_dir2_leaf_trim_data(args, lbp,
                    (xfs_dir2_db_t)(be32_to_cpu(ltp->bestcount) - 1))))
                return error;
        } else
            return 0;
    }
    /*
     * Read the data block if we don't already have it, give up if it fails.
     */
    if (dbp == NULL &&
        (error = xfs_da_read_buf(tp, dp, mp->m_dirdatablk, -1, &dbp,
            XFS_DATA_FORK))) {
        return error;
    }
    hdr = dbp->b_addr;
    ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC));
    /*
     * Size of the "leaf" area in the block.
     */
    size = (uint)sizeof(xfs_dir2_block_tail_t) +
           (uint)sizeof(*lep) * (be16_to_cpu(leaf->hdr.count) - be16_to_cpu(leaf->hdr.stale));
    /*
     * Look at the last data entry.
     */
    tagp = (__be16 *)((char *)hdr + mp->m_dirblksize) - 1;
    dup = (xfs_dir2_data_unused_t *)((char *)hdr + be16_to_cpu(*tagp));
    /*
     * If it's not free or is too short we can't do it.
     */
    if (be16_to_cpu(dup->freetag) != XFS_DIR2_DATA_FREE_TAG ||
        be16_to_cpu(dup->length) < size)
        return 0;

    /*
     * Start converting it to block form.
     */
    hdr->magic = cpu_to_be32(XFS_DIR2_BLOCK_MAGIC);
    needlog = 1;
    needscan = 0;
    /*
     * Use up the space at the end of the block (blp/btp).
     */
    xfs_dir2_data_use_free(tp, dbp, dup, mp->m_dirblksize - size, size,
        &needlog, &needscan);
    /*
     * Initialize the block tail.
     */
    btp = xfs_dir2_block_tail_p(mp, hdr);
    btp->count = cpu_to_be32(be16_to_cpu(leaf->hdr.count) - be16_to_cpu(leaf->hdr.stale));
    btp->stale = 0;
    xfs_dir2_block_log_tail(tp, dbp);
    /*
     * Initialize the block leaf area.  We compact out stale entries.
     */
    lep = xfs_dir2_block_leaf_p(btp);
    for (from = to = 0; from < be16_to_cpu(leaf->hdr.count); from++) {
        if (leaf->ents[from].address ==
            cpu_to_be32(XFS_DIR2_NULL_DATAPTR))
            continue;
        lep[to++] = leaf->ents[from];
    }
    ASSERT(to == be32_to_cpu(btp->count));
    xfs_dir2_block_log_leaf(tp, dbp, 0, be32_to_cpu(btp->count) - 1);
    /*
     * Scan the bestfree if we need it and log the data block header.
     */
    if (needscan)
        xfs_dir2_data_freescan(mp, hdr, &needlog);
    if (needlog)
        xfs_dir2_data_log_header(tp, dbp);
    /*
     * Pitch the old leaf block.
     */
    error = xfs_da_shrink_inode(args, mp->m_dirleafblk, lbp);
    if (error)
        return error;

    /*
     * Now see if the resulting block can be shrunken to shortform.
     */
    size = xfs_dir2_block_sfsize(dp, hdr, &sfh);
    if (size > XFS_IFORK_DSIZE(dp))
        return 0;

    return xfs_dir2_block_to_sf(args, dbp, size, &sfh);
}

/*
 * Convert the shortform directory to block form.
 */
int                     /* error */
xfs_dir2_sf_to_block(
    xfs_da_args_t       *args)      /* operation arguments */
{
    xfs_dir2_db_t       blkno;      /* dir-relative block # (0) */
    xfs_dir2_data_hdr_t *hdr;       /* block header */
    xfs_dir2_leaf_entry_t   *blp;       /* block leaf entries */
    struct xfs_buf      *bp;        /* block buffer */
    xfs_dir2_block_tail_t   *btp;       /* block tail pointer */
    xfs_dir2_data_entry_t   *dep;       /* data entry pointer */
    xfs_inode_t     *dp;        /* incore directory inode */
    int         dummy;      /* trash */
    xfs_dir2_data_unused_t  *dup;       /* unused entry pointer */
    int         endoffset;  /* end of data objects */
    int         error;      /* error return value */
    int         i;      /* index */
    xfs_mount_t     *mp;        /* filesystem mount point */
    int         needlog;    /* need to log block header */
    int         needscan;   /* need to scan block freespc */
    int         newoffset;  /* offset from current entry */
    int         offset;     /* target block offset */
    xfs_dir2_sf_entry_t *sfep;      /* sf entry pointer */
    xfs_dir2_sf_hdr_t   *oldsfp;    /* old shortform header  */
    xfs_dir2_sf_hdr_t   *sfp;       /* shortform header  */
    __be16          *tagp;      /* end of data entry */
    xfs_trans_t     *tp;        /* transaction pointer */
    struct xfs_name     name;

    trace_xfs_dir2_sf_to_block(args);

    dp = args->dp;
    tp = args->trans;
    mp = dp->i_mount;
    ASSERT(dp->i_df.if_flags & XFS_IFINLINE);
    /*
     * Bomb out if the shortform directory is way too short.
     */
    if (dp->i_d.di_size < offsetof(xfs_dir2_sf_hdr_t, parent)) {
        ASSERT(XFS_FORCED_SHUTDOWN(mp));
        return XFS_ERROR(EIO);
    }

    oldsfp = (xfs_dir2_sf_hdr_t *)dp->i_df.if_u1.if_data;

    ASSERT(dp->i_df.if_bytes == dp->i_d.di_size);
    ASSERT(dp->i_df.if_u1.if_data != NULL);
    ASSERT(dp->i_d.di_size >= xfs_dir2_sf_hdr_size(oldsfp->i8count));

    /*
     * Copy the directory into a temporary buffer.
     * Then pitch the incore inode data so we can make extents.
     */
    sfp = kmem_alloc(dp->i_df.if_bytes, KM_SLEEP);
    memcpy(sfp, oldsfp, dp->i_df.if_bytes);

    xfs_idata_realloc(dp, -dp->i_df.if_bytes, XFS_DATA_FORK);
    dp->i_d.di_size = 0;
    xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);

    /*
     * Add block 0 to the inode.
     */
    error = xfs_dir2_grow_inode(args, XFS_DIR2_DATA_SPACE, &blkno);
    if (error) {
        kmem_free(sfp);
        return error;
    }
    /*
     * Initialize the data block.
     */
    error = xfs_dir2_data_init(args, blkno, &bp);
    if (error) {
        kmem_free(sfp);
        return error;
    }
    hdr = bp->b_addr;
    hdr->magic = cpu_to_be32(XFS_DIR2_BLOCK_MAGIC);
    /*
     * Compute size of block "tail" area.
     */
    i = (uint)sizeof(*btp) +
        (sfp->count + 2) * (uint)sizeof(xfs_dir2_leaf_entry_t);
    /*
     * The whole thing is initialized to free by the init routine.
     * Say we're using the leaf and tail area.
     */
    dup = (xfs_dir2_data_unused_t *)(hdr + 1);
    needlog = needscan = 0;
    xfs_dir2_data_use_free(tp, bp, dup, mp->m_dirblksize - i, i, &needlog,
        &needscan);
    ASSERT(needscan == 0);
    /*
     * Fill in the tail.
     */
    btp = xfs_dir2_block_tail_p(mp, hdr);
    btp->count = cpu_to_be32(sfp->count + 2);   /* ., .. */
    btp->stale = 0;
    blp = xfs_dir2_block_leaf_p(btp);
    endoffset = (uint)((char *)blp - (char *)hdr);
    /*
     * Remove the freespace, we'll manage it.
     */
    xfs_dir2_data_use_free(tp, bp, dup,
        (xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr),
        be16_to_cpu(dup->length), &needlog, &needscan);
    /*
     * Create entry for .
     */
    dep = (xfs_dir2_data_entry_t *)
          ((char *)hdr + XFS_DIR2_DATA_DOT_OFFSET);
    dep->inumber = cpu_to_be64(dp->i_ino);
    dep->namelen = 1;
    dep->name[0] = '.';
    tagp = xfs_dir2_data_entry_tag_p(dep);
    *tagp = cpu_to_be16((char *)dep - (char *)hdr);
    xfs_dir2_data_log_entry(tp, bp, dep);
    blp[0].hashval = cpu_to_be32(xfs_dir_hash_dot);
    blp[0].address = cpu_to_be32(xfs_dir2_byte_to_dataptr(mp,
                (char *)dep - (char *)hdr));
    /*
     * Create entry for ..
     */
    dep = (xfs_dir2_data_entry_t *)
        ((char *)hdr + XFS_DIR2_DATA_DOTDOT_OFFSET);
    dep->inumber = cpu_to_be64(xfs_dir2_sf_get_parent_ino(sfp));
    dep->namelen = 2;
    dep->name[0] = dep->name[1] = '.';
    tagp = xfs_dir2_data_entry_tag_p(dep);
    *tagp = cpu_to_be16((char *)dep - (char *)hdr);
    xfs_dir2_data_log_entry(tp, bp, dep);
    blp[1].hashval = cpu_to_be32(xfs_dir_hash_dotdot);
    blp[1].address = cpu_to_be32(xfs_dir2_byte_to_dataptr(mp,
                (char *)dep - (char *)hdr));
    offset = XFS_DIR2_DATA_FIRST_OFFSET;
    /*
     * Loop over existing entries, stuff them in.
     */
    i = 0;
    if (!sfp->count)
        sfep = NULL;
    else
        sfep = xfs_dir2_sf_firstentry(sfp);
    /*
     * Need to preserve the existing offset values in the sf directory.
     * Insert holes (unused entries) where necessary.
     */
    while (offset < endoffset) {
        /*
         * sfep is null when we reach the end of the list.
         */
        if (sfep == NULL)
            newoffset = endoffset;
        else
            newoffset = xfs_dir2_sf_get_offset(sfep);
        /*
         * There should be a hole here, make one.
         */
        if (offset < newoffset) {
            dup = (xfs_dir2_data_unused_t *)((char *)hdr + offset);
            dup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
            dup->length = cpu_to_be16(newoffset - offset);
            *xfs_dir2_data_unused_tag_p(dup) = cpu_to_be16(
                ((char *)dup - (char *)hdr));
            xfs_dir2_data_log_unused(tp, bp, dup);
            xfs_dir2_data_freeinsert(hdr, dup, &dummy);
            offset += be16_to_cpu(dup->length);
            continue;
        }
        /*
         * Copy a real entry.
         */
        dep = (xfs_dir2_data_entry_t *)((char *)hdr + newoffset);
        dep->inumber = cpu_to_be64(xfs_dir2_sfe_get_ino(sfp, sfep));
        dep->namelen = sfep->namelen;
        memcpy(dep->name, sfep->name, dep->namelen);
        tagp = xfs_dir2_data_entry_tag_p(dep);
        *tagp = cpu_to_be16((char *)dep - (char *)hdr);
        xfs_dir2_data_log_entry(tp, bp, dep);
        name.name = sfep->name;
        name.len = sfep->namelen;
        blp[2 + i].hashval = cpu_to_be32(mp->m_dirnameops->
                            hashname(&name));
        blp[2 + i].address = cpu_to_be32(xfs_dir2_byte_to_dataptr(mp,
                         (char *)dep - (char *)hdr));
        offset = (int)((char *)(tagp + 1) - (char *)hdr);
        if (++i == sfp->count)
            sfep = NULL;
        else
            sfep = xfs_dir2_sf_nextentry(sfp, sfep);
    }
    /* Done with the temporary buffer */
    kmem_free(sfp);
    /*
     * Sort the leaf entries by hash value.
     */
    xfs_sort(blp, be32_to_cpu(btp->count), sizeof(*blp), xfs_dir2_block_sort);
    /*
     * Log the leaf entry area and tail.
     * Already logged the header in data_init, ignore needlog.
     */
    ASSERT(needscan == 0);
    xfs_dir2_block_log_leaf(tp, bp, 0, be32_to_cpu(btp->count) - 1);
    xfs_dir2_block_log_tail(tp, bp);
    xfs_dir2_data_check(dp, bp);
    return 0;
}