netfilter: tcp conntrack: fix unacknowledged data detection with NAT

[linux/fpc-iii.git] / fs / xfs / xfs_dir2.c

/*
 * Copyright (c) 2000-2001,2005 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_alloc_btree.h"
#include "xfs_dir2_sf.h"
#include "xfs_attr_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_inode_item.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"
#include "xfs_vnodeops.h"

struct xfs_name xfs_name_dotdot = {"..", 2};

/*
 * ASCII case-insensitive (ie. A-Z) support for directories that was
 * used in IRIX.
 */
STATIC xfs_dahash_t
xfs_ascii_ci_hashname(
        struct xfs_name *name)
{
        xfs_dahash_t    hash;
        int             i;

        for (i = 0, hash = 0; i < name->len; i++)
                hash = tolower(name->name[i]) ^ rol32(hash, 7);

        return hash;
}

STATIC enum xfs_dacmp
xfs_ascii_ci_compname(
        struct xfs_da_args *args,
        const char      *name,
        int             len)
{
        enum xfs_dacmp  result;
        int             i;

        if (args->namelen != len)
                return XFS_CMP_DIFFERENT;

        result = XFS_CMP_EXACT;
        for (i = 0; i < len; i++) {
                if (args->name[i] == name[i])
                        continue;
                if (tolower(args->name[i]) != tolower(name[i]))
                        return XFS_CMP_DIFFERENT;
                result = XFS_CMP_CASE;
        }

        return result;
}

static struct xfs_nameops xfs_ascii_ci_nameops = {
        .hashname       = xfs_ascii_ci_hashname,
        .compname       = xfs_ascii_ci_compname,
};

void
xfs_dir_mount(
        xfs_mount_t     *mp)
{
        ASSERT(xfs_sb_version_hasdirv2(&mp->m_sb));
        ASSERT((1 << (mp->m_sb.sb_blocklog + mp->m_sb.sb_dirblklog)) <=
               XFS_MAX_BLOCKSIZE);
        mp->m_dirblksize = 1 << (mp->m_sb.sb_blocklog + mp->m_sb.sb_dirblklog);
        mp->m_dirblkfsbs = 1 << mp->m_sb.sb_dirblklog;
        mp->m_dirdatablk = xfs_dir2_db_to_da(mp, XFS_DIR2_DATA_FIRSTDB(mp));
        mp->m_dirleafblk = xfs_dir2_db_to_da(mp, XFS_DIR2_LEAF_FIRSTDB(mp));
        mp->m_dirfreeblk = xfs_dir2_db_to_da(mp, XFS_DIR2_FREE_FIRSTDB(mp));
        mp->m_attr_node_ents =
                (mp->m_sb.sb_blocksize - (uint)sizeof(xfs_da_node_hdr_t)) /
                (uint)sizeof(xfs_da_node_entry_t);
        mp->m_dir_node_ents =
                (mp->m_dirblksize - (uint)sizeof(xfs_da_node_hdr_t)) /
                (uint)sizeof(xfs_da_node_entry_t);
        mp->m_dir_magicpct = (mp->m_dirblksize * 37) / 100;
        if (xfs_sb_version_hasasciici(&mp->m_sb))
                mp->m_dirnameops = &xfs_ascii_ci_nameops;
        else
                mp->m_dirnameops = &xfs_default_nameops;
}

/*
 * Return 1 if directory contains only "." and "..".
 */
int
xfs_dir_isempty(
        xfs_inode_t     *dp)
{
        xfs_dir2_sf_t   *sfp;

        ASSERT((dp->i_d.di_mode & S_IFMT) == S_IFDIR);
        if (dp->i_d.di_size == 0)       /* might happen during shutdown. */
                return 1;
        if (dp->i_d.di_size > XFS_IFORK_DSIZE(dp))
                return 0;
        sfp = (xfs_dir2_sf_t *)dp->i_df.if_u1.if_data;
        return !sfp->hdr.count;
}

/*
 * Validate a given inode number.
 */
int
xfs_dir_ino_validate(
        xfs_mount_t     *mp,
        xfs_ino_t       ino)
{
        xfs_agblock_t   agblkno;
        xfs_agino_t     agino;
        xfs_agnumber_t  agno;
        int             ino_ok;
        int             ioff;

        agno = XFS_INO_TO_AGNO(mp, ino);
        agblkno = XFS_INO_TO_AGBNO(mp, ino);
        ioff = XFS_INO_TO_OFFSET(mp, ino);
        agino = XFS_OFFBNO_TO_AGINO(mp, agblkno, ioff);
        ino_ok =
                agno < mp->m_sb.sb_agcount &&
                agblkno < mp->m_sb.sb_agblocks &&
                agblkno != 0 &&
                ioff < (1 << mp->m_sb.sb_inopblog) &&
                XFS_AGINO_TO_INO(mp, agno, agino) == ino;
        if (unlikely(XFS_TEST_ERROR(!ino_ok, mp, XFS_ERRTAG_DIR_INO_VALIDATE,
                        XFS_RANDOM_DIR_INO_VALIDATE))) {
                xfs_fs_cmn_err(CE_WARN, mp, "Invalid inode number 0x%Lx",
                                (unsigned long long) ino);
                XFS_ERROR_REPORT("xfs_dir_ino_validate", XFS_ERRLEVEL_LOW, mp);
                return XFS_ERROR(EFSCORRUPTED);
        }
        return 0;
}

/*
 * Initialize a directory with its "." and ".." entries.
 */
int
xfs_dir_init(
        xfs_trans_t     *tp,
        xfs_inode_t     *dp,
        xfs_inode_t     *pdp)
{
        xfs_da_args_t   args;
        int             error;

        memset((char *)&args, 0, sizeof(args));
        args.dp = dp;
        args.trans = tp;
        ASSERT((dp->i_d.di_mode & S_IFMT) == S_IFDIR);
        if ((error = xfs_dir_ino_validate(tp->t_mountp, pdp->i_ino)))
                return error;
        return xfs_dir2_sf_create(&args, pdp->i_ino);
}

/*
  Enter a name in a directory.
 */
int
xfs_dir_createname(
        xfs_trans_t             *tp,
        xfs_inode_t             *dp,
        struct xfs_name         *name,
        xfs_ino_t               inum,           /* new entry inode number */
        xfs_fsblock_t           *first,         /* bmap's firstblock */
        xfs_bmap_free_t         *flist,         /* bmap's freeblock list */
        xfs_extlen_t            total)          /* bmap's total block count */
{
        xfs_da_args_t           args;
        int                     rval;
        int                     v;              /* type-checking value */

        ASSERT((dp->i_d.di_mode & S_IFMT) == S_IFDIR);
        if ((rval = xfs_dir_ino_validate(tp->t_mountp, inum)))
                return rval;
        XFS_STATS_INC(xs_dir_create);

        memset(&args, 0, sizeof(xfs_da_args_t));
        args.name = name->name;
        args.namelen = name->len;
        args.hashval = dp->i_mount->m_dirnameops->hashname(name);
        args.inumber = inum;
        args.dp = dp;
        args.firstblock = first;
        args.flist = flist;
        args.total = total;
        args.whichfork = XFS_DATA_FORK;
        args.trans = tp;
        args.op_flags = XFS_DA_OP_ADDNAME | XFS_DA_OP_OKNOENT;

        if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
                rval = xfs_dir2_sf_addname(&args);
        else if ((rval = xfs_dir2_isblock(tp, dp, &v)))
                return rval;
        else if (v)
                rval = xfs_dir2_block_addname(&args);
        else if ((rval = xfs_dir2_isleaf(tp, dp, &v)))
                return rval;
        else if (v)
                rval = xfs_dir2_leaf_addname(&args);
        else
                rval = xfs_dir2_node_addname(&args);
        return rval;
}

/*
 * If doing a CI lookup and case-insensitive match, dup actual name into
 * args.value. Return EEXIST for success (ie. name found) or an error.
 */
int
xfs_dir_cilookup_result(
        struct xfs_da_args *args,
        const char      *name,
        int             len)
{
        if (args->cmpresult == XFS_CMP_DIFFERENT)
                return ENOENT;
        if (args->cmpresult != XFS_CMP_CASE ||
                                        !(args->op_flags & XFS_DA_OP_CILOOKUP))
                return EEXIST;

        args->value = kmem_alloc(len, KM_MAYFAIL);
        if (!args->value)
                return ENOMEM;

        memcpy(args->value, name, len);
        args->valuelen = len;
        return EEXIST;
}

/*
 * Lookup a name in a directory, give back the inode number.
 * If ci_name is not NULL, returns the actual name in ci_name if it differs
 * to name, or ci_name->name is set to NULL for an exact match.
 */

int
xfs_dir_lookup(
        xfs_trans_t     *tp,
        xfs_inode_t     *dp,
        struct xfs_name *name,
        xfs_ino_t       *inum,          /* out: inode number */
        struct xfs_name *ci_name)       /* out: actual name if CI match */
{
        xfs_da_args_t   args;
        int             rval;
        int             v;              /* type-checking value */

        ASSERT((dp->i_d.di_mode & S_IFMT) == S_IFDIR);
        XFS_STATS_INC(xs_dir_lookup);

        memset(&args, 0, sizeof(xfs_da_args_t));
        args.name = name->name;
        args.namelen = name->len;
        args.hashval = dp->i_mount->m_dirnameops->hashname(name);
        args.dp = dp;
        args.whichfork = XFS_DATA_FORK;
        args.trans = tp;
        args.op_flags = XFS_DA_OP_OKNOENT;
        if (ci_name)
                args.op_flags |= XFS_DA_OP_CILOOKUP;

        if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
                rval = xfs_dir2_sf_lookup(&args);
        else if ((rval = xfs_dir2_isblock(tp, dp, &v)))
                return rval;
        else if (v)
                rval = xfs_dir2_block_lookup(&args);
        else if ((rval = xfs_dir2_isleaf(tp, dp, &v)))
                return rval;
        else if (v)
                rval = xfs_dir2_leaf_lookup(&args);
        else
                rval = xfs_dir2_node_lookup(&args);
        if (rval == EEXIST)
                rval = 0;
        if (!rval) {
                *inum = args.inumber;
                if (ci_name) {
                        ci_name->name = args.value;
                        ci_name->len = args.valuelen;
                }
        }
        return rval;
}

/*
 * Remove an entry from a directory.
 */
int
xfs_dir_removename(
        xfs_trans_t     *tp,
        xfs_inode_t     *dp,
        struct xfs_name *name,
        xfs_ino_t       ino,
        xfs_fsblock_t   *first,         /* bmap's firstblock */
        xfs_bmap_free_t *flist,         /* bmap's freeblock list */
        xfs_extlen_t    total)          /* bmap's total block count */
{
        xfs_da_args_t   args;
        int             rval;
        int             v;              /* type-checking value */

        ASSERT((dp->i_d.di_mode & S_IFMT) == S_IFDIR);
        XFS_STATS_INC(xs_dir_remove);

        memset(&args, 0, sizeof(xfs_da_args_t));
        args.name = name->name;
        args.namelen = name->len;
        args.hashval = dp->i_mount->m_dirnameops->hashname(name);
        args.inumber = ino;
        args.dp = dp;
        args.firstblock = first;
        args.flist = flist;
        args.total = total;
        args.whichfork = XFS_DATA_FORK;
        args.trans = tp;

        if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
                rval = xfs_dir2_sf_removename(&args);
        else if ((rval = xfs_dir2_isblock(tp, dp, &v)))
                return rval;
        else if (v)
                rval = xfs_dir2_block_removename(&args);
        else if ((rval = xfs_dir2_isleaf(tp, dp, &v)))
                return rval;
        else if (v)
                rval = xfs_dir2_leaf_removename(&args);
        else
                rval = xfs_dir2_node_removename(&args);
        return rval;
}

/*
 * Read a directory.
 */
int
xfs_readdir(
        xfs_inode_t     *dp,
        void            *dirent,
        size_t          bufsize,
        xfs_off_t       *offset,
        filldir_t       filldir)
{
        int             rval;           /* return value */
        int             v;              /* type-checking value */

        xfs_itrace_entry(dp);

        if (XFS_FORCED_SHUTDOWN(dp->i_mount))
                return XFS_ERROR(EIO);

        ASSERT((dp->i_d.di_mode & S_IFMT) == S_IFDIR);
        XFS_STATS_INC(xs_dir_getdents);

        if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
                rval = xfs_dir2_sf_getdents(dp, dirent, offset, filldir);
        else if ((rval = xfs_dir2_isblock(NULL, dp, &v)))
                ;
        else if (v)
                rval = xfs_dir2_block_getdents(dp, dirent, offset, filldir);
        else
                rval = xfs_dir2_leaf_getdents(dp, dirent, bufsize, offset,
                                              filldir);
        return rval;
}

/*
 * Replace the inode number of a directory entry.
 */
int
xfs_dir_replace(
        xfs_trans_t     *tp,
        xfs_inode_t     *dp,
        struct xfs_name *name,          /* name of entry to replace */
        xfs_ino_t       inum,           /* new inode number */
        xfs_fsblock_t   *first,         /* bmap's firstblock */
        xfs_bmap_free_t *flist,         /* bmap's freeblock list */
        xfs_extlen_t    total)          /* bmap's total block count */
{
        xfs_da_args_t   args;
        int             rval;
        int             v;              /* type-checking value */

        ASSERT((dp->i_d.di_mode & S_IFMT) == S_IFDIR);

        if ((rval = xfs_dir_ino_validate(tp->t_mountp, inum)))
                return rval;

        memset(&args, 0, sizeof(xfs_da_args_t));
        args.name = name->name;
        args.namelen = name->len;
        args.hashval = dp->i_mount->m_dirnameops->hashname(name);
        args.inumber = inum;
        args.dp = dp;
        args.firstblock = first;
        args.flist = flist;
        args.total = total;
        args.whichfork = XFS_DATA_FORK;
        args.trans = tp;

        if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
                rval = xfs_dir2_sf_replace(&args);
        else if ((rval = xfs_dir2_isblock(tp, dp, &v)))
                return rval;
        else if (v)
                rval = xfs_dir2_block_replace(&args);
        else if ((rval = xfs_dir2_isleaf(tp, dp, &v)))
                return rval;
        else if (v)
                rval = xfs_dir2_leaf_replace(&args);
        else
                rval = xfs_dir2_node_replace(&args);
        return rval;
}

/*
 * See if this entry can be added to the directory without allocating space.
 * First checks that the caller couldn't reserve enough space (resblks = 0).
 */
int
xfs_dir_canenter(
        xfs_trans_t     *tp,
        xfs_inode_t     *dp,
        struct xfs_name *name,          /* name of entry to add */
        uint            resblks)
{
        xfs_da_args_t   args;
        int             rval;
        int             v;              /* type-checking value */

        if (resblks)
                return 0;

        ASSERT((dp->i_d.di_mode & S_IFMT) == S_IFDIR);

        memset(&args, 0, sizeof(xfs_da_args_t));
        args.name = name->name;
        args.namelen = name->len;
        args.hashval = dp->i_mount->m_dirnameops->hashname(name);
        args.dp = dp;
        args.whichfork = XFS_DATA_FORK;
        args.trans = tp;
        args.op_flags = XFS_DA_OP_JUSTCHECK | XFS_DA_OP_ADDNAME |
                                                        XFS_DA_OP_OKNOENT;

        if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
                rval = xfs_dir2_sf_addname(&args);
        else if ((rval = xfs_dir2_isblock(tp, dp, &v)))
                return rval;
        else if (v)
                rval = xfs_dir2_block_addname(&args);
        else if ((rval = xfs_dir2_isleaf(tp, dp, &v)))
                return rval;
        else if (v)
                rval = xfs_dir2_leaf_addname(&args);
        else
                rval = xfs_dir2_node_addname(&args);
        return rval;
}

/*
 * Utility routines.
 */

/*
 * Add a block to the directory.
 * This routine is for data and free blocks, not leaf/node blocks
 * which are handled by xfs_da_grow_inode.
 */
int
xfs_dir2_grow_inode(
        xfs_da_args_t   *args,
        int             space,          /* v2 dir's space XFS_DIR2_xxx_SPACE */
        xfs_dir2_db_t   *dbp)           /* out: block number added */
{
        xfs_fileoff_t   bno;            /* directory offset of new block */
        int             count;          /* count of filesystem blocks */
        xfs_inode_t     *dp;            /* incore directory inode */
        int             error;
        int             got;            /* blocks actually mapped */
        int             i;
        xfs_bmbt_irec_t map;            /* single structure for bmap */
        int             mapi;           /* mapping index */
        xfs_bmbt_irec_t *mapp;          /* bmap mapping structure(s) */
        xfs_mount_t     *mp;
        int             nmap;           /* number of bmap entries */
        xfs_trans_t     *tp;
        xfs_drfsbno_t   nblks;

        xfs_dir2_trace_args_s("grow_inode", args, space);
        dp = args->dp;
        tp = args->trans;
        mp = dp->i_mount;
        nblks = dp->i_d.di_nblocks;
        /*
         * Set lowest possible block in the space requested.
         */
        bno = XFS_B_TO_FSBT(mp, space * XFS_DIR2_SPACE_SIZE);
        count = mp->m_dirblkfsbs;
        /*
         * Find the first hole for our block.
         */
        if ((error = xfs_bmap_first_unused(tp, dp, count, &bno, XFS_DATA_FORK)))
                return error;
        nmap = 1;
        ASSERT(args->firstblock != NULL);
        /*
         * Try mapping the new block contiguously (one extent).
         */
        if ((error = xfs_bmapi(tp, dp, bno, count,
                        XFS_BMAPI_WRITE|XFS_BMAPI_METADATA|XFS_BMAPI_CONTIG,
                        args->firstblock, args->total, &map, &nmap,
                        args->flist, NULL)))
                return error;
        ASSERT(nmap <= 1);
        if (nmap == 1) {
                mapp = &map;
                mapi = 1;
        }
        /*
         * Didn't work and this is a multiple-fsb directory block.
         * Try again with contiguous flag turned on.
         */
        else if (nmap == 0 && count > 1) {
                xfs_fileoff_t   b;      /* current file offset */

                /*
                 * Space for maximum number of mappings.
                 */
                mapp = kmem_alloc(sizeof(*mapp) * count, KM_SLEEP);
                /*
                 * Iterate until we get to the end of our block.
                 */
                for (b = bno, mapi = 0; b < bno + count; ) {
                        int     c;      /* current fsb count */

                        /*
                         * Can't map more than MAX_NMAP at once.
                         */
                        nmap = MIN(XFS_BMAP_MAX_NMAP, count);
                        c = (int)(bno + count - b);
                        if ((error = xfs_bmapi(tp, dp, b, c,
                                        XFS_BMAPI_WRITE|XFS_BMAPI_METADATA,
                                        args->firstblock, args->total,
                                        &mapp[mapi], &nmap, args->flist,
                                        NULL))) {
                                kmem_free(mapp);
                                return error;
                        }
                        if (nmap < 1)
                                break;
                        /*
                         * Add this bunch into our table, go to the next offset.
                         */
                        mapi += nmap;
                        b = mapp[mapi - 1].br_startoff +
                            mapp[mapi - 1].br_blockcount;
                }
        }
        /*
         * Didn't work.
         */
        else {
                mapi = 0;
                mapp = NULL;
        }
        /*
         * See how many fsb's we got.
         */
        for (i = 0, got = 0; i < mapi; i++)
                got += mapp[i].br_blockcount;
        /*
         * Didn't get enough fsb's, or the first/last block's are wrong.
         */
        if (got != count || mapp[0].br_startoff != bno ||
            mapp[mapi - 1].br_startoff + mapp[mapi - 1].br_blockcount !=
            bno + count) {
                if (mapp != &map)
                        kmem_free(mapp);
                return XFS_ERROR(ENOSPC);
        }
        /*
         * Done with the temporary mapping table.
         */
        if (mapp != &map)
                kmem_free(mapp);

        /* account for newly allocated blocks in reserved blocks total */
        args->total -= dp->i_d.di_nblocks - nblks;
        *dbp = xfs_dir2_da_to_db(mp, (xfs_dablk_t)bno);

        /*
         * Update file's size if this is the data space and it grew.
         */
        if (space == XFS_DIR2_DATA_SPACE) {
                xfs_fsize_t     size;           /* directory file (data) size */

                size = XFS_FSB_TO_B(mp, bno + count);
                if (size > dp->i_d.di_size) {
                        dp->i_d.di_size = size;
                        xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
                }
        }
        return 0;
}

/*
 * See if the directory is a single-block form directory.
 */
int
xfs_dir2_isblock(
        xfs_trans_t     *tp,
        xfs_inode_t     *dp,
        int             *vp)            /* out: 1 is block, 0 is not block */
{
        xfs_fileoff_t   last;           /* last file offset */
        xfs_mount_t     *mp;
        int             rval;

        mp = dp->i_mount;
        if ((rval = xfs_bmap_last_offset(tp, dp, &last, XFS_DATA_FORK)))
                return rval;
        rval = XFS_FSB_TO_B(mp, last) == mp->m_dirblksize;
        ASSERT(rval == 0 || dp->i_d.di_size == mp->m_dirblksize);
        *vp = rval;
        return 0;
}

/*
 * See if the directory is a single-leaf form directory.
 */
int
xfs_dir2_isleaf(
        xfs_trans_t     *tp,
        xfs_inode_t     *dp,
        int             *vp)            /* out: 1 is leaf, 0 is not leaf */
{
        xfs_fileoff_t   last;           /* last file offset */
        xfs_mount_t     *mp;
        int             rval;

        mp = dp->i_mount;
        if ((rval = xfs_bmap_last_offset(tp, dp, &last, XFS_DATA_FORK)))
                return rval;
        *vp = last == mp->m_dirleafblk + (1 << mp->m_sb.sb_dirblklog);
        return 0;
}

/*
 * Remove the given block from the directory.
 * This routine is used for data and free blocks, leaf/node are done
 * by xfs_da_shrink_inode.
 */
int
xfs_dir2_shrink_inode(
        xfs_da_args_t   *args,
        xfs_dir2_db_t   db,
        xfs_dabuf_t     *bp)
{
        xfs_fileoff_t   bno;            /* directory file offset */
        xfs_dablk_t     da;             /* directory file offset */
        int             done;           /* bunmap is finished */
        xfs_inode_t     *dp;
        int             error;
        xfs_mount_t     *mp;
        xfs_trans_t     *tp;

        xfs_dir2_trace_args_db("shrink_inode", args, db, bp);
        dp = args->dp;
        mp = dp->i_mount;
        tp = args->trans;
        da = xfs_dir2_db_to_da(mp, db);
        /*
         * Unmap the fsblock(s).
         */
        if ((error = xfs_bunmapi(tp, dp, da, mp->m_dirblkfsbs,
                        XFS_BMAPI_METADATA, 0, args->firstblock, args->flist,
                        NULL, &done))) {
                /*
                 * ENOSPC actually can happen if we're in a removename with
                 * no space reservation, and the resulting block removal
                 * would cause a bmap btree split or conversion from extents
                 * to btree.  This can only happen for un-fragmented
                 * directory blocks, since you need to be punching out
                 * the middle of an extent.
                 * In this case we need to leave the block in the file,
                 * and not binval it.
                 * So the block has to be in a consistent empty state
                 * and appropriately logged.
                 * We don't free up the buffer, the caller can tell it
                 * hasn't happened since it got an error back.
                 */
                return error;
        }
        ASSERT(done);
        /*
         * Invalidate the buffer from the transaction.
         */
        xfs_da_binval(tp, bp);
        /*
         * If it's not a data block, we're done.
         */
        if (db >= XFS_DIR2_LEAF_FIRSTDB(mp))
                return 0;
        /*
         * If the block isn't the last one in the directory, we're done.
         */
        if (dp->i_d.di_size > xfs_dir2_db_off_to_byte(mp, db + 1, 0))
                return 0;
        bno = da;
        if ((error = xfs_bmap_last_before(tp, dp, &bno, XFS_DATA_FORK))) {
                /*
                 * This can't really happen unless there's kernel corruption.
                 */
                return error;
        }
        if (db == mp->m_dirdatablk)
                ASSERT(bno == 0);
        else
                ASSERT(bno > 0);
        /*
         * Set the size to the new last block.
         */
        dp->i_d.di_size = XFS_FSB_TO_B(mp, bno);
        xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE);
        return 0;
}