// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
 * Copyright (c) 2013 Red Hat, Inc.
 * All Rights Reserved.
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_dir2.h"
#include "xfs_dir2_priv.h"
#include "xfs_error.h"
#include "xfs_trans.h"
#include "xfs_buf_item.h"
#include "xfs_log.h"

static xfs_failaddr_t xfs_dir2_data_freefind_verify(
                struct xfs_dir2_data_hdr *hdr, struct xfs_dir2_data_free *bf,
                struct xfs_dir2_data_unused *dup,
                struct xfs_dir2_data_free **bf_ent);

struct xfs_dir2_data_free *
xfs_dir2_data_bestfree_p(
        struct xfs_mount                *mp,
        struct xfs_dir2_data_hdr        *hdr)
{
        if (xfs_has_crc(mp))
                return ((struct xfs_dir3_data_hdr *)hdr)->best_free;
        return hdr->bestfree;
}

/*
 * Pointer to an entry's tag word.
 */
__be16 *
xfs_dir2_data_entry_tag_p(
        struct xfs_mount                *mp,
        struct xfs_dir2_data_entry      *dep)
{
        return (__be16 *)((char *)dep +
                xfs_dir2_data_entsize(mp, dep->namelen) - sizeof(__be16));
}

uint8_t
xfs_dir2_data_get_ftype(
        struct xfs_mount                *mp,
        struct xfs_dir2_data_entry      *dep)
{
        if (xfs_has_ftype(mp)) {
                uint8_t                 ftype = dep->name[dep->namelen];

                if (likely(ftype < XFS_DIR3_FT_MAX))
                        return ftype;
        }

        return XFS_DIR3_FT_UNKNOWN;
}

void
xfs_dir2_data_put_ftype(
        struct xfs_mount                *mp,
        struct xfs_dir2_data_entry      *dep,
        uint8_t                         ftype)
{
        ASSERT(ftype < XFS_DIR3_FT_MAX);
        ASSERT(dep->namelen != 0);

        if (xfs_has_ftype(mp))
                dep->name[dep->namelen] = ftype;
}

/*
 * The number of leaf entries is limited by the size of the block and the amount
 * of space used by the data entries.  We don't know how much space is used by
 * the data entries yet, so just ensure that the count falls somewhere inside
 * the block right now.
 */
static inline unsigned int
xfs_dir2_data_max_leaf_entries(
        struct xfs_da_geometry          *geo)
{
        return (geo->blksize - sizeof(struct xfs_dir2_block_tail) -
                geo->data_entry_offset) /
                        sizeof(struct xfs_dir2_leaf_entry);
}

/*
 * Check the consistency of the data block.
 * The input can also be a block-format directory.
 * Return NULL if the buffer is good, otherwise the address of the error.
 */
xfs_failaddr_t
__xfs_dir3_data_check(
        struct xfs_inode        *dp,            /* incore inode pointer */
        struct xfs_buf          *bp)            /* data block's buffer */
{
        xfs_dir2_dataptr_t      addr;           /* addr for leaf lookup */
        xfs_dir2_data_free_t    *bf;            /* bestfree table */
        xfs_dir2_block_tail_t   *btp=NULL;      /* block tail */
        int                     count;          /* count of entries found */
        xfs_dir2_data_hdr_t     *hdr;           /* data block header */
        xfs_dir2_data_free_t    *dfp;           /* bestfree entry */
        int                     freeseen;       /* mask of bestfrees seen */
        xfs_dahash_t            hash;           /* hash of current name */
        int                     i;              /* leaf index */
        int                     lastfree;       /* last entry was unused */
        xfs_dir2_leaf_entry_t   *lep=NULL;      /* block leaf entries */
        struct xfs_mount        *mp = bp->b_mount;
        int                     stale;          /* count of stale leaves */
        struct xfs_name         name;
        unsigned int            offset;
        unsigned int            end;
        struct xfs_da_geometry  *geo = mp->m_dir_geo;

        /*
         * If this isn't a directory, something is seriously wrong.  Bail out.
         */
        if (dp && !S_ISDIR(VFS_I(dp)->i_mode))
                return __this_address;

        hdr = bp->b_addr;
        offset = geo->data_entry_offset;

        switch (hdr->magic) {
        case cpu_to_be32(XFS_DIR3_BLOCK_MAGIC):
        case cpu_to_be32(XFS_DIR2_BLOCK_MAGIC):
                btp = xfs_dir2_block_tail_p(geo, hdr);
                lep = xfs_dir2_block_leaf_p(btp);

                if (be32_to_cpu(btp->count) >=
                    xfs_dir2_data_max_leaf_entries(geo))
                        return __this_address;
                break;
        case cpu_to_be32(XFS_DIR3_DATA_MAGIC):
        case cpu_to_be32(XFS_DIR2_DATA_MAGIC):
                break;
        default:
                return __this_address;
        }
        end = xfs_dir3_data_end_offset(geo, hdr);
        if (!end)
                return __this_address;

        /*
         * Account for zero bestfree entries.
         */
        bf = xfs_dir2_data_bestfree_p(mp, hdr);
        count = lastfree = freeseen = 0;
        if (!bf[0].length) {
                if (bf[0].offset)
                        return __this_address;
                freeseen |= 1 << 0;
        }
        if (!bf[1].length) {
                if (bf[1].offset)
                        return __this_address;
                freeseen |= 1 << 1;
        }
        if (!bf[2].length) {
                if (bf[2].offset)
                        return __this_address;
                freeseen |= 1 << 2;
        }

        if (be16_to_cpu(bf[0].length) < be16_to_cpu(bf[1].length))
                return __this_address;
        if (be16_to_cpu(bf[1].length) < be16_to_cpu(bf[2].length))
                return __this_address;
        /*
         * Loop over the data/unused entries.
         */
        while (offset < end) {
                struct xfs_dir2_data_unused     *dup = bp->b_addr + offset;
                struct xfs_dir2_data_entry      *dep = bp->b_addr + offset;

                /*
                 * If it's unused, look for the space in the bestfree table.
                 * If we find it, account for that, else make sure it
                 * doesn't need to be there.
                 */
                if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
                        xfs_failaddr_t  fa;

                        if (lastfree != 0)
                                return __this_address;
                        if (offset + be16_to_cpu(dup->length) > end)
                                return __this_address;
                        if (be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)) !=
                            offset)
                                return __this_address;
                        fa = xfs_dir2_data_freefind_verify(hdr, bf, dup, &dfp);
                        if (fa)
                                return fa;
                        if (dfp) {
                                i = (int)(dfp - bf);
                                if ((freeseen & (1 << i)) != 0)
                                        return __this_address;
                                freeseen |= 1 << i;
                        } else {
                                if (be16_to_cpu(dup->length) >
                                    be16_to_cpu(bf[2].length))
                                        return __this_address;
                        }
                        offset += be16_to_cpu(dup->length);
                        lastfree = 1;
                        continue;
                }
                /*
                 * It's a real entry.  Validate the fields.
                 * If this is a block directory then make sure it's
                 * in the leaf section of the block.
                 * The linear search is crude but this is DEBUG code.
                 */
                if (dep->namelen == 0)
                        return __this_address;
                if (!xfs_verify_dir_ino(mp, be64_to_cpu(dep->inumber)))
                        return __this_address;
                if (offset + xfs_dir2_data_entsize(mp, dep->namelen) > end)
                        return __this_address;
                if (be16_to_cpu(*xfs_dir2_data_entry_tag_p(mp, dep)) != offset)
                        return __this_address;
                if (xfs_dir2_data_get_ftype(mp, dep) >= XFS_DIR3_FT_MAX)
                        return __this_address;
                count++;
                lastfree = 0;
                if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC) ||
                    hdr->magic == cpu_to_be32(XFS_DIR3_BLOCK_MAGIC)) {
                        addr = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
                                                (xfs_dir2_data_aoff_t)
                                                ((char *)dep - (char *)hdr));
                        name.name = dep->name;
                        name.len = dep->namelen;
                        hash = xfs_dir2_hashname(mp, &name);
                        for (i = 0; i < be32_to_cpu(btp->count); i++) {
                                if (be32_to_cpu(lep[i].address) == addr &&
                                    be32_to_cpu(lep[i].hashval) == hash)
                                        break;
                        }
                        if (i >= be32_to_cpu(btp->count))
                                return __this_address;
                }
                offset += xfs_dir2_data_entsize(mp, dep->namelen);
        }
        /*
         * Need to have seen all the entries and all the bestfree slots.
         */
        if (freeseen != 7)
                return __this_address;
        if (hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC) ||
            hdr->magic == cpu_to_be32(XFS_DIR3_BLOCK_MAGIC)) {
                for (i = stale = 0; i < be32_to_cpu(btp->count); i++) {
                        if (lep[i].address ==
                            cpu_to_be32(XFS_DIR2_NULL_DATAPTR))
                                stale++;
                        if (i > 0 && be32_to_cpu(lep[i].hashval) <
                                     be32_to_cpu(lep[i - 1].hashval))
                                return __this_address;
                }
                if (count != be32_to_cpu(btp->count) - be32_to_cpu(btp->stale))
                        return __this_address;
                if (stale != be32_to_cpu(btp->stale))
                        return __this_address;
        }
        return NULL;
}

#ifdef DEBUG
void
xfs_dir3_data_check(
        struct xfs_inode        *dp,
        struct xfs_buf          *bp)
{
        xfs_failaddr_t          fa;

        fa = __xfs_dir3_data_check(dp, bp);
        if (!fa)
                return;
        xfs_corruption_error(__func__, XFS_ERRLEVEL_LOW, dp->i_mount,
                        bp->b_addr, BBTOB(bp->b_length), __FILE__, __LINE__,
                        fa);
        ASSERT(0);
}
#endif

static xfs_failaddr_t
xfs_dir3_data_verify(
        struct xfs_buf          *bp)
{
        struct xfs_mount        *mp = bp->b_mount;
        struct xfs_dir3_blk_hdr *hdr3 = bp->b_addr;

        if (!xfs_verify_magic(bp, hdr3->magic))
                return __this_address;

        if (xfs_has_crc(mp)) {
                if (!uuid_equal(&hdr3->uuid, &mp->m_sb.sb_meta_uuid))
                        return __this_address;
                if (be64_to_cpu(hdr3->blkno) != xfs_buf_daddr(bp))
                        return __this_address;
                if (!xfs_log_check_lsn(mp, be64_to_cpu(hdr3->lsn)))
                        return __this_address;
        }
        return __xfs_dir3_data_check(NULL, bp);
}

/*
 * Readahead of the first block of the directory when it is opened is completely
 * oblivious to the format of the directory. Hence we can either get a block
 * format buffer or a data format buffer on readahead.
 */
static void
xfs_dir3_data_reada_verify(
        struct xfs_buf          *bp)
{
        struct xfs_dir2_data_hdr *hdr = bp->b_addr;

        switch (hdr->magic) {
        case cpu_to_be32(XFS_DIR2_BLOCK_MAGIC):
        case cpu_to_be32(XFS_DIR3_BLOCK_MAGIC):
                bp->b_ops = &xfs_dir3_block_buf_ops;
                bp->b_ops->verify_read(bp);
                return;
        case cpu_to_be32(XFS_DIR2_DATA_MAGIC):
        case cpu_to_be32(XFS_DIR3_DATA_MAGIC):
                bp->b_ops = &xfs_dir3_data_buf_ops;
                bp->b_ops->verify_read(bp);
                return;
        default:
                xfs_verifier_error(bp, -EFSCORRUPTED, __this_address);
                break;
        }
}

static void
xfs_dir3_data_read_verify(
        struct xfs_buf  *bp)
{
        struct xfs_mount        *mp = bp->b_mount;
        xfs_failaddr_t          fa;

        if (xfs_has_crc(mp) &&
            !xfs_buf_verify_cksum(bp, XFS_DIR3_DATA_CRC_OFF))
                xfs_verifier_error(bp, -EFSBADCRC, __this_address);
        else {
                fa = xfs_dir3_data_verify(bp);
                if (fa)
                        xfs_verifier_error(bp, -EFSCORRUPTED, fa);
        }
}

static void
xfs_dir3_data_write_verify(
        struct xfs_buf  *bp)
{
        struct xfs_mount        *mp = bp->b_mount;
        struct xfs_buf_log_item *bip = bp->b_log_item;
        struct xfs_dir3_blk_hdr *hdr3 = bp->b_addr;
        xfs_failaddr_t          fa;

        fa = xfs_dir3_data_verify(bp);
        if (fa) {
                xfs_verifier_error(bp, -EFSCORRUPTED, fa);
                return;
        }

        if (!xfs_has_crc(mp))
                return;

        if (bip)
                hdr3->lsn = cpu_to_be64(bip->bli_item.li_lsn);

        xfs_buf_update_cksum(bp, XFS_DIR3_DATA_CRC_OFF);
}

const struct xfs_buf_ops xfs_dir3_data_buf_ops = {
        .name = "xfs_dir3_data",
        .magic = { cpu_to_be32(XFS_DIR2_DATA_MAGIC),
                   cpu_to_be32(XFS_DIR3_DATA_MAGIC) },
        .verify_read = xfs_dir3_data_read_verify,
        .verify_write = xfs_dir3_data_write_verify,
        .verify_struct = xfs_dir3_data_verify,
};

static const struct xfs_buf_ops xfs_dir3_data_reada_buf_ops = {
        .name = "xfs_dir3_data_reada",
        .magic = { cpu_to_be32(XFS_DIR2_DATA_MAGIC),
                   cpu_to_be32(XFS_DIR3_DATA_MAGIC) },
        .verify_read = xfs_dir3_data_reada_verify,
        .verify_write = xfs_dir3_data_write_verify,
};

static xfs_failaddr_t
xfs_dir3_data_header_check(
        struct xfs_inode        *dp,
        struct xfs_buf          *bp)
{
        struct xfs_mount        *mp = dp->i_mount;

        if (xfs_has_crc(mp)) {
                struct xfs_dir3_data_hdr *hdr3 = bp->b_addr;

                if (be64_to_cpu(hdr3->hdr.owner) != dp->i_ino)
                        return __this_address;
        }

        return NULL;
}

int
xfs_dir3_data_read(
        struct xfs_trans        *tp,
        struct xfs_inode        *dp,
        xfs_dablk_t             bno,
        unsigned int            flags,
        struct xfs_buf          **bpp)
{
        xfs_failaddr_t          fa;
        int                     err;

        err = xfs_da_read_buf(tp, dp, bno, flags, bpp, XFS_DATA_FORK,
                        &xfs_dir3_data_buf_ops);
        if (err || !*bpp)
                return err;

        /* Check things that we can't do in the verifier. */
        fa = xfs_dir3_data_header_check(dp, *bpp);
        if (fa) {
                __xfs_buf_mark_corrupt(*bpp, fa);
                xfs_trans_brelse(tp, *bpp);
                *bpp = NULL;
                return -EFSCORRUPTED;
        }

        xfs_trans_buf_set_type(tp, *bpp, XFS_BLFT_DIR_DATA_BUF);
        return err;
}

int
xfs_dir3_data_readahead(
        struct xfs_inode        *dp,
        xfs_dablk_t             bno,
        unsigned int            flags)
{
        return xfs_da_reada_buf(dp, bno, flags, XFS_DATA_FORK,
                                &xfs_dir3_data_reada_buf_ops);
}

/*
 * Find the bestfree entry that exactly coincides with unused directory space
 * or a verifier error because the bestfree data are bad.
 */
static xfs_failaddr_t
xfs_dir2_data_freefind_verify(
        struct xfs_dir2_data_hdr        *hdr,
        struct xfs_dir2_data_free       *bf,
        struct xfs_dir2_data_unused     *dup,
        struct xfs_dir2_data_free       **bf_ent)
{
        struct xfs_dir2_data_free       *dfp;
        xfs_dir2_data_aoff_t            off;
        bool                            matched = false;
        bool                            seenzero = false;

        *bf_ent = NULL;
        off = (xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr);

        /*
         * Validate some consistency in the bestfree table.
         * Check order, non-overlapping entries, and if we find the
         * one we're looking for it has to be exact.
         */
        for (dfp = &bf[0]; dfp < &bf[XFS_DIR2_DATA_FD_COUNT]; dfp++) {
                if (!dfp->offset) {
                        if (dfp->length)
                                return __this_address;
                        seenzero = true;
                        continue;
                }
                if (seenzero)
                        return __this_address;
                if (be16_to_cpu(dfp->offset) == off) {
                        matched = true;
                        if (dfp->length != dup->length)
                                return __this_address;
                } else if (be16_to_cpu(dfp->offset) > off) {
                        if (off + be16_to_cpu(dup->length) >
                                        be16_to_cpu(dfp->offset))
                                return __this_address;
                } else {
                        if (be16_to_cpu(dfp->offset) +
                                        be16_to_cpu(dfp->length) > off)
                                return __this_address;
                }
                if (!matched &&
                    be16_to_cpu(dfp->length) < be16_to_cpu(dup->length))
                        return __this_address;
                if (dfp > &bf[0] &&
                    be16_to_cpu(dfp[-1].length) < be16_to_cpu(dfp[0].length))
                        return __this_address;
        }

        /* Looks ok so far; now try to match up with a bestfree entry. */
        *bf_ent = xfs_dir2_data_freefind(hdr, bf, dup);
        return NULL;
}

/*
 * Given a data block and an unused entry from that block,
 * return the bestfree entry if any that corresponds to it.
 */
xfs_dir2_data_free_t *
xfs_dir2_data_freefind(
        struct xfs_dir2_data_hdr *hdr,          /* data block header */
        struct xfs_dir2_data_free *bf,          /* bestfree table pointer */
        struct xfs_dir2_data_unused *dup)       /* unused space */
{
        xfs_dir2_data_free_t    *dfp;           /* bestfree entry */
        xfs_dir2_data_aoff_t    off;            /* offset value needed */

        off = (xfs_dir2_data_aoff_t)((char *)dup - (char *)hdr);

        /*
         * If this is smaller than the smallest bestfree entry,
         * it can't be there since they're sorted.
         */
        if (be16_to_cpu(dup->length) <
            be16_to_cpu(bf[XFS_DIR2_DATA_FD_COUNT - 1].length))
                return NULL;
        /*
         * Look at the three bestfree entries for our guy.
         */
        for (dfp = &bf[0]; dfp < &bf[XFS_DIR2_DATA_FD_COUNT]; dfp++) {
                if (!dfp->offset)
                        return NULL;
                if (be16_to_cpu(dfp->offset) == off)
                        return dfp;
        }
        /*
         * Didn't find it.  This only happens if there are duplicate lengths.
         */
        return NULL;
}

/*
 * Insert an unused-space entry into the bestfree table.
 */
xfs_dir2_data_free_t *                          /* entry inserted */
xfs_dir2_data_freeinsert(
        struct xfs_dir2_data_hdr *hdr,          /* data block pointer */
        struct xfs_dir2_data_free *dfp,         /* bestfree table pointer */
        struct xfs_dir2_data_unused *dup,       /* unused space */
        int                     *loghead)       /* log the data header (out) */
{
        xfs_dir2_data_free_t    new;            /* new bestfree entry */

        ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR3_DATA_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR3_BLOCK_MAGIC));

        new.length = dup->length;
        new.offset = cpu_to_be16((char *)dup - (char *)hdr);

        /*
         * Insert at position 0, 1, or 2; or not at all.
         */
        if (be16_to_cpu(new.length) > be16_to_cpu(dfp[0].length)) {
                dfp[2] = dfp[1];
                dfp[1] = dfp[0];
                dfp[0] = new;
                *loghead = 1;
                return &dfp[0];
        }
        if (be16_to_cpu(new.length) > be16_to_cpu(dfp[1].length)) {
                dfp[2] = dfp[1];
                dfp[1] = new;
                *loghead = 1;
                return &dfp[1];
        }
        if (be16_to_cpu(new.length) > be16_to_cpu(dfp[2].length)) {
                dfp[2] = new;
                *loghead = 1;
                return &dfp[2];
        }
        return NULL;
}

/*
 * Remove a bestfree entry from the table.
 */
STATIC void
xfs_dir2_data_freeremove(
        struct xfs_dir2_data_hdr *hdr,          /* data block header */
        struct xfs_dir2_data_free *bf,          /* bestfree table pointer */
        struct xfs_dir2_data_free *dfp,         /* bestfree entry pointer */
        int                     *loghead)       /* out: log data header */
{

        ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR3_DATA_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR3_BLOCK_MAGIC));

        /*
         * It's the first entry, slide the next 2 up.
         */
        if (dfp == &bf[0]) {
                bf[0] = bf[1];
                bf[1] = bf[2];
        }
        /*
         * It's the second entry, slide the 3rd entry up.
         */
        else if (dfp == &bf[1])
                bf[1] = bf[2];
        /*
         * Must be the last entry.
         */
        else
                ASSERT(dfp == &bf[2]);
        /*
         * Clear the 3rd entry, must be zero now.
         */
        bf[2].length = 0;
        bf[2].offset = 0;
        *loghead = 1;
}

/*
 * Given a data block, reconstruct its bestfree map.
 */
void
xfs_dir2_data_freescan(
        struct xfs_mount                *mp,
        struct xfs_dir2_data_hdr        *hdr,
        int                             *loghead)
{
        struct xfs_da_geometry          *geo = mp->m_dir_geo;
        struct xfs_dir2_data_free       *bf = xfs_dir2_data_bestfree_p(mp, hdr);
        void                            *addr = hdr;
        unsigned int                    offset = geo->data_entry_offset;
        unsigned int                    end;

        ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR3_DATA_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR3_BLOCK_MAGIC));

        /*
         * Start by clearing the table.
         */
        memset(bf, 0, sizeof(*bf) * XFS_DIR2_DATA_FD_COUNT);
        *loghead = 1;

        end = xfs_dir3_data_end_offset(geo, addr);
        while (offset < end) {
                struct xfs_dir2_data_unused     *dup = addr + offset;
                struct xfs_dir2_data_entry      *dep = addr + offset;

                /*
                 * If it's a free entry, insert it.
                 */
                if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
                        ASSERT(offset ==
                               be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)));
                        xfs_dir2_data_freeinsert(hdr, bf, dup, loghead);
                        offset += be16_to_cpu(dup->length);
                        continue;
                }

                /*
                 * For active entries, check their tags and skip them.
                 */
                ASSERT(offset ==
                       be16_to_cpu(*xfs_dir2_data_entry_tag_p(mp, dep)));
                offset += xfs_dir2_data_entsize(mp, dep->namelen);
        }
}

/*
 * Initialize a data block at the given block number in the directory.
 * Give back the buffer for the created block.
 */
int                                             /* error */
xfs_dir3_data_init(
        struct xfs_da_args              *args,  /* directory operation args */
        xfs_dir2_db_t                   blkno,  /* logical dir block number */
        struct xfs_buf                  **bpp)  /* output block buffer */
{
        struct xfs_trans                *tp = args->trans;
        struct xfs_inode                *dp = args->dp;
        struct xfs_mount                *mp = dp->i_mount;
        struct xfs_da_geometry          *geo = args->geo;
        struct xfs_buf                  *bp;
        struct xfs_dir2_data_hdr        *hdr;
        struct xfs_dir2_data_unused     *dup;
        struct xfs_dir2_data_free       *bf;
        int                             error;
        int                             i;

        /*
         * Get the buffer set up for the block.
         */
        error = xfs_da_get_buf(tp, dp, xfs_dir2_db_to_da(args->geo, blkno),
                               &bp, XFS_DATA_FORK);
        if (error)
                return error;
        bp->b_ops = &xfs_dir3_data_buf_ops;
        xfs_trans_buf_set_type(tp, bp, XFS_BLFT_DIR_DATA_BUF);

        /*
         * Initialize the header.
         */
        hdr = bp->b_addr;
        if (xfs_has_crc(mp)) {
                struct xfs_dir3_blk_hdr *hdr3 = bp->b_addr;

                memset(hdr3, 0, sizeof(*hdr3));
                hdr3->magic = cpu_to_be32(XFS_DIR3_DATA_MAGIC);
                hdr3->blkno = cpu_to_be64(xfs_buf_daddr(bp));
                hdr3->owner = cpu_to_be64(dp->i_ino);
                uuid_copy(&hdr3->uuid, &mp->m_sb.sb_meta_uuid);

        } else
                hdr->magic = cpu_to_be32(XFS_DIR2_DATA_MAGIC);

        bf = xfs_dir2_data_bestfree_p(mp, hdr);
        bf[0].offset = cpu_to_be16(geo->data_entry_offset);
        bf[0].length = cpu_to_be16(geo->blksize - geo->data_entry_offset);
        for (i = 1; i < XFS_DIR2_DATA_FD_COUNT; i++) {
                bf[i].length = 0;
                bf[i].offset = 0;
        }

        /*
         * Set up an unused entry for the block's body.
         */
        dup = bp->b_addr + geo->data_entry_offset;
        dup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
        dup->length = bf[0].length;
        *xfs_dir2_data_unused_tag_p(dup) = cpu_to_be16((char *)dup - (char *)hdr);

        /*
         * Log it and return it.
         */
        xfs_dir2_data_log_header(args, bp);
        xfs_dir2_data_log_unused(args, bp, dup);
        *bpp = bp;
        return 0;
}

/*
 * Log an active data entry from the block.
 */
void
xfs_dir2_data_log_entry(
        struct xfs_da_args      *args,
        struct xfs_buf          *bp,
        xfs_dir2_data_entry_t   *dep)           /* data entry pointer */
{
        struct xfs_mount        *mp = bp->b_mount;
        struct xfs_dir2_data_hdr *hdr = bp->b_addr;

        ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR3_DATA_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR3_BLOCK_MAGIC));

        xfs_trans_log_buf(args->trans, bp, (uint)((char *)dep - (char *)hdr),
                (uint)((char *)(xfs_dir2_data_entry_tag_p(mp, dep) + 1) -
                       (char *)hdr - 1));
}

/*
 * Log a data block header.
 */
void
xfs_dir2_data_log_header(
        struct xfs_da_args      *args,
        struct xfs_buf          *bp)
{
#ifdef DEBUG
        struct xfs_dir2_data_hdr *hdr = bp->b_addr;

        ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR3_DATA_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR3_BLOCK_MAGIC));
#endif

        xfs_trans_log_buf(args->trans, bp, 0, args->geo->data_entry_offset - 1);
}

/*
 * Log a data unused entry.
 */
void
xfs_dir2_data_log_unused(
        struct xfs_da_args      *args,
        struct xfs_buf          *bp,
        xfs_dir2_data_unused_t  *dup)           /* data unused pointer */
{
        xfs_dir2_data_hdr_t     *hdr = bp->b_addr;

        ASSERT(hdr->magic == cpu_to_be32(XFS_DIR2_DATA_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR3_DATA_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR2_BLOCK_MAGIC) ||
               hdr->magic == cpu_to_be32(XFS_DIR3_BLOCK_MAGIC));

        /*
         * Log the first part of the unused entry.
         */
        xfs_trans_log_buf(args->trans, bp, (uint)((char *)dup - (char *)hdr),
                (uint)((char *)&dup->length + sizeof(dup->length) -
                       1 - (char *)hdr));
        /*
         * Log the end (tag) of the unused entry.
         */
        xfs_trans_log_buf(args->trans, bp,
                (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)hdr),
                (uint)((char *)xfs_dir2_data_unused_tag_p(dup) - (char *)hdr +
                       sizeof(xfs_dir2_data_off_t) - 1));
}

/*
 * Make a byte range in the data block unused.
 * Its current contents are unimportant.
 */
void
xfs_dir2_data_make_free(
        struct xfs_da_args      *args,
        struct xfs_buf          *bp,
        xfs_dir2_data_aoff_t    offset,         /* starting byte offset */
        xfs_dir2_data_aoff_t    len,            /* length in bytes */
        int                     *needlogp,      /* out: log header */
        int                     *needscanp)     /* out: regen bestfree */
{
        xfs_dir2_data_hdr_t     *hdr;           /* data block pointer */
        xfs_dir2_data_free_t    *dfp;           /* bestfree pointer */
        int                     needscan;       /* need to regen bestfree */
        xfs_dir2_data_unused_t  *newdup;        /* new unused entry */
        xfs_dir2_data_unused_t  *postdup;       /* unused entry after us */
        xfs_dir2_data_unused_t  *prevdup;       /* unused entry before us */
        unsigned int            end;
        struct xfs_dir2_data_free *bf;

        hdr = bp->b_addr;

        /*
         * Figure out where the end of the data area is.
         */
        end = xfs_dir3_data_end_offset(args->geo, hdr);
        ASSERT(end != 0);

        /*
         * If this isn't the start of the block, then back up to
         * the previous entry and see if it's free.
         */
        if (offset > args->geo->data_entry_offset) {
                __be16                  *tagp;  /* tag just before us */

                tagp = (__be16 *)((char *)hdr + offset) - 1;
                prevdup = (xfs_dir2_data_unused_t *)((char *)hdr + be16_to_cpu(*tagp));
                if (be16_to_cpu(prevdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
                        prevdup = NULL;
        } else
                prevdup = NULL;
        /*
         * If this isn't the end of the block, see if the entry after
         * us is free.
         */
        if (offset + len < end) {
                postdup =
                        (xfs_dir2_data_unused_t *)((char *)hdr + offset + len);
                if (be16_to_cpu(postdup->freetag) != XFS_DIR2_DATA_FREE_TAG)
                        postdup = NULL;
        } else
                postdup = NULL;
        ASSERT(*needscanp == 0);
        needscan = 0;
        /*
         * Previous and following entries are both free,
         * merge everything into a single free entry.
         */
        bf = xfs_dir2_data_bestfree_p(args->dp->i_mount, hdr);
        if (prevdup && postdup) {
                xfs_dir2_data_free_t    *dfp2;  /* another bestfree pointer */

                /*
                 * See if prevdup and/or postdup are in bestfree table.
                 */
                dfp = xfs_dir2_data_freefind(hdr, bf, prevdup);
                dfp2 = xfs_dir2_data_freefind(hdr, bf, postdup);
                /*
                 * We need a rescan unless there are exactly 2 free entries
                 * namely our two.  Then we know what's happening, otherwise
                 * since the third bestfree is there, there might be more
                 * entries.
                 */
                needscan = (bf[2].length != 0);
                /*
                 * Fix up the new big freespace.
                 */
                be16_add_cpu(&prevdup->length, len + be16_to_cpu(postdup->length));
                *xfs_dir2_data_unused_tag_p(prevdup) =
                        cpu_to_be16((char *)prevdup - (char *)hdr);
                xfs_dir2_data_log_unused(args, bp, prevdup);
                if (!needscan) {
                        /*
                         * Has to be the case that entries 0 and 1 are
                         * dfp and dfp2 (don't know which is which), and
                         * entry 2 is empty.
                         * Remove entry 1 first then entry 0.
                         */
                        ASSERT(dfp && dfp2);
                        if (dfp == &bf[1]) {
                                dfp = &bf[0];
                                ASSERT(dfp2 == dfp);
                                dfp2 = &bf[1];
                        }
                        xfs_dir2_data_freeremove(hdr, bf, dfp2, needlogp);
                        xfs_dir2_data_freeremove(hdr, bf, dfp, needlogp);
                        /*
                         * Now insert the new entry.
                         */
                        dfp = xfs_dir2_data_freeinsert(hdr, bf, prevdup,
                                                       needlogp);
                        ASSERT(dfp == &bf[0]);
                        ASSERT(dfp->length == prevdup->length);
                        ASSERT(!dfp[1].length);
                        ASSERT(!dfp[2].length);
                }
        }
        /*
         * The entry before us is free, merge with it.
         */
        else if (prevdup) {
                dfp = xfs_dir2_data_freefind(hdr, bf, prevdup);
                be16_add_cpu(&prevdup->length, len);
                *xfs_dir2_data_unused_tag_p(prevdup) =
                        cpu_to_be16((char *)prevdup - (char *)hdr);
                xfs_dir2_data_log_unused(args, bp, prevdup);
                /*
                 * If the previous entry was in the table, the new entry
                 * is longer, so it will be in the table too.  Remove
                 * the old one and add the new one.
                 */
                if (dfp) {
                        xfs_dir2_data_freeremove(hdr, bf, dfp, needlogp);
                        xfs_dir2_data_freeinsert(hdr, bf, prevdup, needlogp);
                }
                /*
                 * Otherwise we need a scan if the new entry is big enough.
                 */
                else {
                        needscan = be16_to_cpu(prevdup->length) >
                                   be16_to_cpu(bf[2].length);
                }
        }
        /*
         * The following entry is free, merge with it.
         */
        else if (postdup) {
                dfp = xfs_dir2_data_freefind(hdr, bf, postdup);
                newdup = (xfs_dir2_data_unused_t *)((char *)hdr + offset);
                newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
                newdup->length = cpu_to_be16(len + be16_to_cpu(postdup->length));
                *xfs_dir2_data_unused_tag_p(newdup) =
                        cpu_to_be16((char *)newdup - (char *)hdr);
                xfs_dir2_data_log_unused(args, bp, newdup);
                /*
                 * If the following entry was in the table, the new entry
                 * is longer, so it will be in the table too.  Remove
                 * the old one and add the new one.
                 */
                if (dfp) {
                        xfs_dir2_data_freeremove(hdr, bf, dfp, needlogp);
                        xfs_dir2_data_freeinsert(hdr, bf, newdup, needlogp);
                }
                /*
                 * Otherwise we need a scan if the new entry is big enough.
                 */
                else {
                        needscan = be16_to_cpu(newdup->length) >
                                   be16_to_cpu(bf[2].length);
                }
        }
        /*
         * Neither neighbor is free.  Make a new entry.
         */
        else {
                newdup = (xfs_dir2_data_unused_t *)((char *)hdr + offset);
                newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
                newdup->length = cpu_to_be16(len);
                *xfs_dir2_data_unused_tag_p(newdup) =

                        cpu_to_be16((char *)newdup - (char *)hdr);
                xfs_dir2_data_log_unused(args, bp, newdup);
                xfs_dir2_data_freeinsert(hdr, bf, newdup, needlogp);
        }
        *needscanp = needscan;
}

/* Check our free data for obvious signs of corruption. */
static inline xfs_failaddr_t
xfs_dir2_data_check_free(
        struct xfs_dir2_data_hdr        *hdr,
        struct xfs_dir2_data_unused     *dup,
        xfs_dir2_data_aoff_t            offset,
        xfs_dir2_data_aoff_t            len)
{
        if (hdr->magic != cpu_to_be32(XFS_DIR2_DATA_MAGIC) &&
            hdr->magic != cpu_to_be32(XFS_DIR3_DATA_MAGIC) &&
            hdr->magic != cpu_to_be32(XFS_DIR2_BLOCK_MAGIC) &&
            hdr->magic != cpu_to_be32(XFS_DIR3_BLOCK_MAGIC))
                return __this_address;
        if (be16_to_cpu(dup->freetag) != XFS_DIR2_DATA_FREE_TAG)
                return __this_address;
        if (offset < (char *)dup - (char *)hdr)
                return __this_address;
        if (offset + len > (char *)dup + be16_to_cpu(dup->length) - (char *)hdr)
                return __this_address;
        if ((char *)dup - (char *)hdr !=
                        be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)))
                return __this_address;
        return NULL;
}

/* Sanity-check a new bestfree entry. */
static inline xfs_failaddr_t
xfs_dir2_data_check_new_free(
        struct xfs_dir2_data_hdr        *hdr,
        struct xfs_dir2_data_free       *dfp,
        struct xfs_dir2_data_unused     *newdup)
{
        if (dfp == NULL)
                return __this_address;
        if (dfp->length != newdup->length)
                return __this_address;
        if (be16_to_cpu(dfp->offset) != (char *)newdup - (char *)hdr)
                return __this_address;
        return NULL;
}

/*
 * Take a byte range out of an existing unused space and make it un-free.
 */
int
xfs_dir2_data_use_free(
        struct xfs_da_args      *args,
        struct xfs_buf          *bp,
        xfs_dir2_data_unused_t  *dup,           /* unused entry */
        xfs_dir2_data_aoff_t    offset,         /* starting offset to use */
        xfs_dir2_data_aoff_t    len,            /* length to use */
        int                     *needlogp,      /* out: need to log header */
        int                     *needscanp)     /* out: need regen bestfree */
{
        xfs_dir2_data_hdr_t     *hdr;           /* data block header */
        xfs_dir2_data_free_t    *dfp;           /* bestfree pointer */
        xfs_dir2_data_unused_t  *newdup;        /* new unused entry */
        xfs_dir2_data_unused_t  *newdup2;       /* another new unused entry */
        struct xfs_dir2_data_free *bf;
        xfs_failaddr_t          fa;
        int                     matchback;      /* matches end of freespace */
        int                     matchfront;     /* matches start of freespace */
        int                     needscan;       /* need to regen bestfree */
        int                     oldlen;         /* old unused entry's length */

        hdr = bp->b_addr;
        fa = xfs_dir2_data_check_free(hdr, dup, offset, len);
        if (fa)
                goto corrupt;
        /*
         * Look up the entry in the bestfree table.
         */
        oldlen = be16_to_cpu(dup->length);
        bf = xfs_dir2_data_bestfree_p(args->dp->i_mount, hdr);
        dfp = xfs_dir2_data_freefind(hdr, bf, dup);
        ASSERT(dfp || oldlen <= be16_to_cpu(bf[2].length));
        /*
         * Check for alignment with front and back of the entry.
         */
        matchfront = (char *)dup - (char *)hdr == offset;
        matchback = (char *)dup + oldlen - (char *)hdr == offset + len;
        ASSERT(*needscanp == 0);
        needscan = 0;
        /*
         * If we matched it exactly we just need to get rid of it from
         * the bestfree table.
         */
        if (matchfront && matchback) {
                if (dfp) {
                        needscan = (bf[2].offset != 0);
                        if (!needscan)
                                xfs_dir2_data_freeremove(hdr, bf, dfp,
                                                         needlogp);
                }
        }
        /*
         * We match the first part of the entry.
         * Make a new entry with the remaining freespace.
         */
        else if (matchfront) {
                newdup = (xfs_dir2_data_unused_t *)((char *)hdr + offset + len);
                newdup->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
                newdup->length = cpu_to_be16(oldlen - len);
                *xfs_dir2_data_unused_tag_p(newdup) =
                        cpu_to_be16((char *)newdup - (char *)hdr);
                xfs_dir2_data_log_unused(args, bp, newdup);
                /*
                 * If it was in the table, remove it and add the new one.
                 */
                if (dfp) {
                        xfs_dir2_data_freeremove(hdr, bf, dfp, needlogp);
                        dfp = xfs_dir2_data_freeinsert(hdr, bf, newdup,
                                                       needlogp);
                        fa = xfs_dir2_data_check_new_free(hdr, dfp, newdup);
                        if (fa)
                                goto corrupt;
                        /*
                         * If we got inserted at the last slot,
                         * that means we don't know if there was a better
                         * choice for the last slot, or not.  Rescan.
                         */
                        needscan = dfp == &bf[2];
                }
        }
        /*
         * We match the last part of the entry.
         * Trim the allocated space off the tail of the entry.
         */
        else if (matchback) {
                newdup = dup;
                newdup->length = cpu_to_be16(((char *)hdr + offset) - (char *)newdup);
                *xfs_dir2_data_unused_tag_p(newdup) =
                        cpu_to_be16((char *)newdup - (char *)hdr);
                xfs_dir2_data_log_unused(args, bp, newdup);
                /*
                 * If it was in the table, remove it and add the new one.
                 */
                if (dfp) {
                        xfs_dir2_data_freeremove(hdr, bf, dfp, needlogp);
                        dfp = xfs_dir2_data_freeinsert(hdr, bf, newdup,
                                                       needlogp);
                        fa = xfs_dir2_data_check_new_free(hdr, dfp, newdup);
                        if (fa)
                                goto corrupt;
                        /*
                         * If we got inserted at the last slot,
                         * that means we don't know if there was a better
                         * choice for the last slot, or not.  Rescan.
                         */
                        needscan = dfp == &bf[2];
                }
        }
        /*
         * Poking out the middle of an entry.
         * Make two new entries.
         */
        else {
                newdup = dup;
                newdup->length = cpu_to_be16(((char *)hdr + offset) - (char *)newdup);
                *xfs_dir2_data_unused_tag_p(newdup) =
                        cpu_to_be16((char *)newdup - (char *)hdr);
                xfs_dir2_data_log_unused(args, bp, newdup);
                newdup2 = (xfs_dir2_data_unused_t *)((char *)hdr + offset + len);
                newdup2->freetag = cpu_to_be16(XFS_DIR2_DATA_FREE_TAG);
                newdup2->length = cpu_to_be16(oldlen - len - be16_to_cpu(newdup->length));
                *xfs_dir2_data_unused_tag_p(newdup2) =
                        cpu_to_be16((char *)newdup2 - (char *)hdr);
                xfs_dir2_data_log_unused(args, bp, newdup2);
                /*
                 * If the old entry was in the table, we need to scan
                 * if the 3rd entry was valid, since these entries
                 * are smaller than the old one.
                 * If we don't need to scan that means there were 1 or 2
                 * entries in the table, and removing the old and adding
                 * the 2 new will work.
                 */
                if (dfp) {
                        needscan = (bf[2].length != 0);
                        if (!needscan) {
                                xfs_dir2_data_freeremove(hdr, bf, dfp,
                                                         needlogp);
                                xfs_dir2_data_freeinsert(hdr, bf, newdup,
                                                         needlogp);
                                xfs_dir2_data_freeinsert(hdr, bf, newdup2,
                                                         needlogp);
                        }
                }
        }
        *needscanp = needscan;
        return 0;
corrupt:
        xfs_corruption_error(__func__, XFS_ERRLEVEL_LOW, args->dp->i_mount,
                        hdr, sizeof(*hdr), __FILE__, __LINE__, fa);
        return -EFSCORRUPTED;
}

/* Find the end of the entry data in a data/block format dir block. */
unsigned int
xfs_dir3_data_end_offset(
        struct xfs_da_geometry          *geo,
        struct xfs_dir2_data_hdr        *hdr)
{
        void                            *p;

        switch (hdr->magic) {
        case cpu_to_be32(XFS_DIR3_BLOCK_MAGIC):
        case cpu_to_be32(XFS_DIR2_BLOCK_MAGIC):
                p = xfs_dir2_block_leaf_p(xfs_dir2_block_tail_p(geo, hdr));
                return p - (void *)hdr;
        case cpu_to_be32(XFS_DIR3_DATA_MAGIC):
        case cpu_to_be32(XFS_DIR2_DATA_MAGIC):
                return geo->blksize;
        default:
                return 0;
        }
}