// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2017 Oracle.  All Rights Reserved.
 * Author: Darrick J. Wong <darrick.wong@oracle.com>
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_log_format.h"
#include "xfs_trans.h"
#include "xfs_inode.h"
#include "xfs_icache.h"
#include "xfs_dir2.h"
#include "xfs_dir2_priv.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/dabtree.h"

/* Set us up to scrub directories. */
int
xchk_setup_directory(
        struct xfs_scrub        *sc,
        struct xfs_inode        *ip)
{
        return xchk_setup_inode_contents(sc, ip, 0);
}

/* Directories */

/* Scrub a directory entry. */

struct xchk_dir_ctx {
        /* VFS fill-directory iterator */
        struct dir_context      dir_iter;

        struct xfs_scrub        *sc;
};

/* Check that an inode's mode matches a given DT_ type. */
STATIC int
xchk_dir_check_ftype(
        struct xchk_dir_ctx     *sdc,
        xfs_fileoff_t           offset,
        xfs_ino_t               inum,
        int                     dtype)
{
        struct xfs_mount        *mp = sdc->sc->mp;
        struct xfs_inode        *ip;
        int                     ino_dtype;
        int                     error = 0;

        if (!xfs_sb_version_hasftype(&mp->m_sb)) {
                if (dtype != DT_UNKNOWN && dtype != DT_DIR)
                        xchk_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK,
                                        offset);
                goto out;
        }

        /*
         * Grab the inode pointed to by the dirent.  We release the
         * inode before we cancel the scrub transaction.  Since we're
         * don't know a priori that releasing the inode won't trigger
         * eofblocks cleanup (which allocates what would be a nested
         * transaction), we can't use DONTCACHE here because DONTCACHE
         * inodes can trigger immediate inactive cleanup of the inode.
         */
        error = xfs_iget(mp, sdc->sc->tp, inum, 0, 0, &ip);
        if (!xchk_fblock_xref_process_error(sdc->sc, XFS_DATA_FORK, offset,
                        &error))
                goto out;

        /* Convert mode to the DT_* values that dir_emit uses. */
        ino_dtype = xfs_dir3_get_dtype(mp,
                        xfs_mode_to_ftype(VFS_I(ip)->i_mode));
        if (ino_dtype != dtype)
                xchk_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK, offset);
        xfs_irele(ip);
out:
        return error;
}

/*
 * Scrub a single directory entry.
 *
 * We use the VFS directory iterator (i.e. readdir) to call this
 * function for every directory entry in a directory.  Once we're here,
 * we check the inode number to make sure it's sane, then we check that
 * we can look up this filename.  Finally, we check the ftype.
 */
STATIC int
xchk_dir_actor(
        struct dir_context      *dir_iter,
        const char              *name,
        int                     namelen,
        loff_t                  pos,
        u64                     ino,
        unsigned                type)
{
        struct xfs_mount        *mp;
        struct xfs_inode        *ip;
        struct xchk_dir_ctx     *sdc;
        struct xfs_name         xname;
        xfs_ino_t               lookup_ino;
        xfs_dablk_t             offset;
        int                     error = 0;

        sdc = container_of(dir_iter, struct xchk_dir_ctx, dir_iter);
        ip = sdc->sc->ip;
        mp = ip->i_mount;
        offset = xfs_dir2_db_to_da(mp->m_dir_geo,
                        xfs_dir2_dataptr_to_db(mp->m_dir_geo, pos));

        if (xchk_should_terminate(sdc->sc, &error))
                return error;

        /* Does this inode number make sense? */
        if (!xfs_verify_dir_ino(mp, ino)) {
                xchk_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK, offset);
                goto out;
        }

        /* Does this name make sense? */
        if (!xfs_dir2_namecheck(name, namelen)) {
                xchk_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK, offset);
                goto out;
        }

        if (!strncmp(".", name, namelen)) {
                /* If this is "." then check that the inum matches the dir. */
                if (xfs_sb_version_hasftype(&mp->m_sb) && type != DT_DIR)
                        xchk_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK,
                                        offset);
                if (ino != ip->i_ino)
                        xchk_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK,
                                        offset);
        } else if (!strncmp("..", name, namelen)) {
                /*
                 * If this is ".." in the root inode, check that the inum
                 * matches this dir.
                 */
                if (xfs_sb_version_hasftype(&mp->m_sb) && type != DT_DIR)
                        xchk_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK,
                                        offset);
                if (ip->i_ino == mp->m_sb.sb_rootino && ino != ip->i_ino)
                        xchk_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK,
                                        offset);
        }

        /* Verify that we can look up this name by hash. */
        xname.name = name;
        xname.len = namelen;
        xname.type = XFS_DIR3_FT_UNKNOWN;

        error = xfs_dir_lookup(sdc->sc->tp, ip, &xname, &lookup_ino, NULL);
        /* ENOENT means the hash lookup failed and the dir is corrupt */
        if (error == -ENOENT)
                error = -EFSCORRUPTED;
        if (!xchk_fblock_process_error(sdc->sc, XFS_DATA_FORK, offset,
                        &error))
                goto out;
        if (lookup_ino != ino) {
                xchk_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK, offset);
                goto out;
        }

        /* Verify the file type.  This function absorbs error codes. */
        error = xchk_dir_check_ftype(sdc, offset, lookup_ino, type);
        if (error)
                goto out;
out:
        /*
         * A negative error code returned here is supposed to cause the
         * dir_emit caller (xfs_readdir) to abort the directory iteration
         * and return zero to xchk_directory.
         */
        if (error == 0 && sdc->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                return -EFSCORRUPTED;
        return error;
}

/* Scrub a directory btree record. */
STATIC int
xchk_dir_rec(
        struct xchk_da_btree            *ds,
        int                             level)
{
        struct xfs_da_state_blk         *blk = &ds->state->path.blk[level];
        struct xfs_mount                *mp = ds->state->mp;
        struct xfs_inode                *dp = ds->dargs.dp;
        struct xfs_da_geometry          *geo = mp->m_dir_geo;
        struct xfs_dir2_data_entry      *dent;
        struct xfs_buf                  *bp;
        struct xfs_dir2_leaf_entry      *ent;
        unsigned int                    end;
        unsigned int                    iter_off;
        xfs_ino_t                       ino;
        xfs_dablk_t                     rec_bno;
        xfs_dir2_db_t                   db;
        xfs_dir2_data_aoff_t            off;
        xfs_dir2_dataptr_t              ptr;
        xfs_dahash_t                    calc_hash;
        xfs_dahash_t                    hash;
        struct xfs_dir3_icleaf_hdr      hdr;
        unsigned int                    tag;
        int                             error;

        ASSERT(blk->magic == XFS_DIR2_LEAF1_MAGIC ||
               blk->magic == XFS_DIR2_LEAFN_MAGIC);

        xfs_dir2_leaf_hdr_from_disk(mp, &hdr, blk->bp->b_addr);
        ent = hdr.ents + blk->index;

        /* Check the hash of the entry. */
        error = xchk_da_btree_hash(ds, level, &ent->hashval);
        if (error)
                goto out;

        /* Valid hash pointer? */
        ptr = be32_to_cpu(ent->address);
        if (ptr == 0)
                return 0;

        /* Find the directory entry's location. */
        db = xfs_dir2_dataptr_to_db(geo, ptr);
        off = xfs_dir2_dataptr_to_off(geo, ptr);
        rec_bno = xfs_dir2_db_to_da(geo, db);

        if (rec_bno >= geo->leafblk) {
                xchk_da_set_corrupt(ds, level);
                goto out;
        }
        error = xfs_dir3_data_read(ds->dargs.trans, dp, rec_bno,
                        XFS_DABUF_MAP_HOLE_OK, &bp);
        if (!xchk_fblock_process_error(ds->sc, XFS_DATA_FORK, rec_bno,
                        &error))
                goto out;
        if (!bp) {
                xchk_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno);
                goto out;
        }
        xchk_buffer_recheck(ds->sc, bp);

        if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                goto out_relse;

        dent = bp->b_addr + off;

        /* Make sure we got a real directory entry. */
        iter_off = geo->data_entry_offset;
        end = xfs_dir3_data_end_offset(geo, bp->b_addr);
        if (!end) {
                xchk_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno);
                goto out_relse;
        }
        for (;;) {
                struct xfs_dir2_data_entry      *dep = bp->b_addr + iter_off;
                struct xfs_dir2_data_unused     *dup = bp->b_addr + iter_off;

                if (iter_off >= end) {
                        xchk_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno);
                        goto out_relse;
                }

                if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
                        iter_off += be16_to_cpu(dup->length);
                        continue;
                }
                if (dep == dent)
                        break;
                iter_off += xfs_dir2_data_entsize(mp, dep->namelen);
        }

        /* Retrieve the entry, sanity check it, and compare hashes. */
        ino = be64_to_cpu(dent->inumber);
        hash = be32_to_cpu(ent->hashval);
        tag = be16_to_cpup(xfs_dir2_data_entry_tag_p(mp, dent));
        if (!xfs_verify_dir_ino(mp, ino) || tag != off)
                xchk_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno);
        if (dent->namelen == 0) {
                xchk_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno);
                goto out_relse;
        }
        calc_hash = xfs_da_hashname(dent->name, dent->namelen);
        if (calc_hash != hash)
                xchk_fblock_set_corrupt(ds->sc, XFS_DATA_FORK, rec_bno);

out_relse:
        xfs_trans_brelse(ds->dargs.trans, bp);
out:
        return error;
}

/*
 * Is this unused entry either in the bestfree or smaller than all of
 * them?  We've already checked that the bestfrees are sorted longest to
 * shortest, and that there aren't any bogus entries.
 */
STATIC void
xchk_directory_check_free_entry(
        struct xfs_scrub                *sc,
        xfs_dablk_t                     lblk,
        struct xfs_dir2_data_free       *bf,
        struct xfs_dir2_data_unused     *dup)
{
        struct xfs_dir2_data_free       *dfp;
        unsigned int                    dup_length;

        dup_length = be16_to_cpu(dup->length);

        /* Unused entry is shorter than any of the bestfrees */
        if (dup_length < be16_to_cpu(bf[XFS_DIR2_DATA_FD_COUNT - 1].length))
                return;

        for (dfp = &bf[XFS_DIR2_DATA_FD_COUNT - 1]; dfp >= bf; dfp--)
                if (dup_length == be16_to_cpu(dfp->length))
                        return;

        /* Unused entry should be in the bestfrees but wasn't found. */
        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
}

/* Check free space info in a directory data block. */
STATIC int
xchk_directory_data_bestfree(
        struct xfs_scrub                *sc,
        xfs_dablk_t                     lblk,
        bool                            is_block)
{
        struct xfs_dir2_data_unused     *dup;
        struct xfs_dir2_data_free       *dfp;
        struct xfs_buf                  *bp;
        struct xfs_dir2_data_free       *bf;
        struct xfs_mount                *mp = sc->mp;
        u16                             tag;
        unsigned int                    nr_bestfrees = 0;
        unsigned int                    nr_frees = 0;
        unsigned int                    smallest_bestfree;
        int                             newlen;
        unsigned int                    offset;
        unsigned int                    end;
        int                             error;

        if (is_block) {
                /* dir block format */
                if (lblk != XFS_B_TO_FSBT(mp, XFS_DIR2_DATA_OFFSET))
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
                error = xfs_dir3_block_read(sc->tp, sc->ip, &bp);
        } else {
                /* dir data format */
                error = xfs_dir3_data_read(sc->tp, sc->ip, lblk, 0, &bp);
        }
        if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, lblk, &error))
                goto out;
        xchk_buffer_recheck(sc, bp);

        /* XXX: Check xfs_dir3_data_hdr.pad is zero once we start setting it. */

        if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                goto out_buf;

        /* Do the bestfrees correspond to actual free space? */
        bf = xfs_dir2_data_bestfree_p(mp, bp->b_addr);
        smallest_bestfree = UINT_MAX;
        for (dfp = &bf[0]; dfp < &bf[XFS_DIR2_DATA_FD_COUNT]; dfp++) {
                offset = be16_to_cpu(dfp->offset);
                if (offset == 0)
                        continue;
                if (offset >= mp->m_dir_geo->blksize) {
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
                        goto out_buf;
                }
                dup = bp->b_addr + offset;
                tag = be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup));

                /* bestfree doesn't match the entry it points at? */
                if (dup->freetag != cpu_to_be16(XFS_DIR2_DATA_FREE_TAG) ||
                    be16_to_cpu(dup->length) != be16_to_cpu(dfp->length) ||
                    tag != offset) {
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
                        goto out_buf;
                }

                /* bestfree records should be ordered largest to smallest */
                if (smallest_bestfree < be16_to_cpu(dfp->length)) {
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
                        goto out_buf;
                }

                smallest_bestfree = be16_to_cpu(dfp->length);
                nr_bestfrees++;
        }

        /* Make sure the bestfrees are actually the best free spaces. */
        offset = mp->m_dir_geo->data_entry_offset;
        end = xfs_dir3_data_end_offset(mp->m_dir_geo, bp->b_addr);

        /* Iterate the entries, stopping when we hit or go past the end. */
        while (offset < end) {
                dup = bp->b_addr + offset;

                /* Skip real entries */
                if (dup->freetag != cpu_to_be16(XFS_DIR2_DATA_FREE_TAG)) {
                        struct xfs_dir2_data_entry *dep = bp->b_addr + offset;

                        newlen = xfs_dir2_data_entsize(mp, dep->namelen);
                        if (newlen <= 0) {
                                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK,
                                                lblk);
                                goto out_buf;
                        }
                        offset += newlen;
                        continue;
                }

                /* Spot check this free entry */
                tag = be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup));
                if (tag != offset) {
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
                        goto out_buf;
                }

                /*
                 * Either this entry is a bestfree or it's smaller than
                 * any of the bestfrees.
                 */
                xchk_directory_check_free_entry(sc, lblk, bf, dup);
                if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                        goto out_buf;

                /* Move on. */
                newlen = be16_to_cpu(dup->length);
                if (newlen <= 0) {
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
                        goto out_buf;
                }
                offset += newlen;
                if (offset <= end)
                        nr_frees++;
        }

        /* We're required to fill all the space. */
        if (offset != end)
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

        /* Did we see at least as many free slots as there are bestfrees? */
        if (nr_frees < nr_bestfrees)
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
out_buf:
        xfs_trans_brelse(sc->tp, bp);
out:
        return error;
}

/*
 * Does the free space length in the free space index block ($len) match
 * the longest length in the directory data block's bestfree array?
 * Assume that we've already checked that the data block's bestfree
 * array is in order.
 */
STATIC void
xchk_directory_check_freesp(
        struct xfs_scrub                *sc,
        xfs_dablk_t                     lblk,
        struct xfs_buf                  *dbp,
        unsigned int                    len)
{
        struct xfs_dir2_data_free       *dfp;

        dfp = xfs_dir2_data_bestfree_p(sc->mp, dbp->b_addr);

        if (len != be16_to_cpu(dfp->length))
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);

        if (len > 0 && be16_to_cpu(dfp->offset) == 0)
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
}

/* Check free space info in a directory leaf1 block. */
STATIC int
xchk_directory_leaf1_bestfree(
        struct xfs_scrub                *sc,
        struct xfs_da_args              *args,
        xfs_dablk_t                     lblk)
{
        struct xfs_dir3_icleaf_hdr      leafhdr;
        struct xfs_dir2_leaf_tail       *ltp;
        struct xfs_dir2_leaf            *leaf;
        struct xfs_buf                  *dbp;
        struct xfs_buf                  *bp;
        struct xfs_da_geometry          *geo = sc->mp->m_dir_geo;
        __be16                          *bestp;
        __u16                           best;
        __u32                           hash;
        __u32                           lasthash = 0;
        __u32                           bestcount;
        unsigned int                    stale = 0;
        int                             i;
        int                             error;

        /* Read the free space block. */
        error = xfs_dir3_leaf_read(sc->tp, sc->ip, lblk, &bp);
        if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, lblk, &error))
                return error;
        xchk_buffer_recheck(sc, bp);

        leaf = bp->b_addr;
        xfs_dir2_leaf_hdr_from_disk(sc->ip->i_mount, &leafhdr, leaf);
        ltp = xfs_dir2_leaf_tail_p(geo, leaf);
        bestcount = be32_to_cpu(ltp->bestcount);
        bestp = xfs_dir2_leaf_bests_p(ltp);

        if (xfs_sb_version_hascrc(&sc->mp->m_sb)) {
                struct xfs_dir3_leaf_hdr        *hdr3 = bp->b_addr;

                if (hdr3->pad != cpu_to_be32(0))
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
        }

        /*
         * There should be as many bestfree slots as there are dir data
         * blocks that can fit under i_size.
         */
        if (bestcount != xfs_dir2_byte_to_db(geo, sc->ip->i_d.di_size)) {
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
                goto out;
        }

        /* Is the leaf count even remotely sane? */
        if (leafhdr.count > geo->leaf_max_ents) {
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
                goto out;
        }

        /* Leaves and bests don't overlap in leaf format. */
        if ((char *)&leafhdr.ents[leafhdr.count] > (char *)bestp) {
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
                goto out;
        }

        /* Check hash value order, count stale entries.  */
        for (i = 0; i < leafhdr.count; i++) {
                hash = be32_to_cpu(leafhdr.ents[i].hashval);
                if (i > 0 && lasthash > hash)
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
                lasthash = hash;
                if (leafhdr.ents[i].address ==
                    cpu_to_be32(XFS_DIR2_NULL_DATAPTR))
                        stale++;
        }
        if (leafhdr.stale != stale)
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
        if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                goto out;

        /* Check all the bestfree entries. */
        for (i = 0; i < bestcount; i++, bestp++) {
                best = be16_to_cpu(*bestp);
                if (best == NULLDATAOFF)
                        continue;
                error = xfs_dir3_data_read(sc->tp, sc->ip,
                                i * args->geo->fsbcount, 0, &dbp);
                if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, lblk,
                                &error))
                        break;
                xchk_directory_check_freesp(sc, lblk, dbp, best);
                xfs_trans_brelse(sc->tp, dbp);
                if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                        break;
        }
out:
        xfs_trans_brelse(sc->tp, bp);
        return error;
}

/* Check free space info in a directory freespace block. */
STATIC int
xchk_directory_free_bestfree(
        struct xfs_scrub                *sc,
        struct xfs_da_args              *args,
        xfs_dablk_t                     lblk)
{
        struct xfs_dir3_icfree_hdr      freehdr;
        struct xfs_buf                  *dbp;
        struct xfs_buf                  *bp;
        __u16                           best;
        unsigned int                    stale = 0;
        int                             i;
        int                             error;

        /* Read the free space block */
        error = xfs_dir2_free_read(sc->tp, sc->ip, lblk, &bp);
        if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, lblk, &error))
                return error;
        xchk_buffer_recheck(sc, bp);

        if (xfs_sb_version_hascrc(&sc->mp->m_sb)) {
                struct xfs_dir3_free_hdr        *hdr3 = bp->b_addr;

                if (hdr3->pad != cpu_to_be32(0))
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
        }

        /* Check all the entries. */
        xfs_dir2_free_hdr_from_disk(sc->ip->i_mount, &freehdr, bp->b_addr);
        for (i = 0; i < freehdr.nvalid; i++) {
                best = be16_to_cpu(freehdr.bests[i]);
                if (best == NULLDATAOFF) {
                        stale++;
                        continue;
                }
                error = xfs_dir3_data_read(sc->tp, sc->ip,
                                (freehdr.firstdb + i) * args->geo->fsbcount,
                                0, &dbp);
                if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, lblk,
                                &error))
                        goto out;
                xchk_directory_check_freesp(sc, lblk, dbp, best);
                xfs_trans_brelse(sc->tp, dbp);
        }

        if (freehdr.nused + stale != freehdr.nvalid)
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
out:
        xfs_trans_brelse(sc->tp, bp);
        return error;
}

/* Check free space information in directories. */
STATIC int
xchk_directory_blocks(
        struct xfs_scrub        *sc)
{
        struct xfs_bmbt_irec    got;
        struct xfs_da_args      args;
        struct xfs_ifork        *ifp = XFS_IFORK_PTR(sc->ip, XFS_DATA_FORK);
        struct xfs_mount        *mp = sc->mp;
        xfs_fileoff_t           leaf_lblk;
        xfs_fileoff_t           free_lblk;
        xfs_fileoff_t           lblk;
        struct xfs_iext_cursor  icur;
        xfs_dablk_t             dabno;
        bool                    found;
        int                     is_block = 0;
        int                     error;

        /* Ignore local format directories. */
        if (ifp->if_format != XFS_DINODE_FMT_EXTENTS &&
            ifp->if_format != XFS_DINODE_FMT_BTREE)
                return 0;

        lblk = XFS_B_TO_FSB(mp, XFS_DIR2_DATA_OFFSET);
        leaf_lblk = XFS_B_TO_FSB(mp, XFS_DIR2_LEAF_OFFSET);
        free_lblk = XFS_B_TO_FSB(mp, XFS_DIR2_FREE_OFFSET);

        /* Is this a block dir? */
        args.dp = sc->ip;
        args.geo = mp->m_dir_geo;
        args.trans = sc->tp;
        error = xfs_dir2_isblock(&args, &is_block);
        if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, lblk, &error))
                goto out;

        /* Iterate all the data extents in the directory... */
        found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
        while (found && !(sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)) {
                /* Block directories only have a single block at offset 0. */
                if (is_block &&
                    (got.br_startoff > 0 ||
                     got.br_blockcount != args.geo->fsbcount)) {
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK,
                                        got.br_startoff);
                        break;
                }

                /* No more data blocks... */
                if (got.br_startoff >= leaf_lblk)
                        break;

                /*
                 * Check each data block's bestfree data.
                 *
                 * Iterate all the fsbcount-aligned block offsets in
                 * this directory.  The directory block reading code is
                 * smart enough to do its own bmap lookups to handle
                 * discontiguous directory blocks.  When we're done
                 * with the extent record, re-query the bmap at the
                 * next fsbcount-aligned offset to avoid redundant
                 * block checks.
                 */
                for (lblk = roundup((xfs_dablk_t)got.br_startoff,
                                args.geo->fsbcount);
                     lblk < got.br_startoff + got.br_blockcount;
                     lblk += args.geo->fsbcount) {
                        error = xchk_directory_data_bestfree(sc, lblk,
                                        is_block);
                        if (error)
                                goto out;
                }
                dabno = got.br_startoff + got.br_blockcount;
                lblk = roundup(dabno, args.geo->fsbcount);
                found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
        }

        if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                goto out;

        /* Look for a leaf1 block, which has free info. */
        if (xfs_iext_lookup_extent(sc->ip, ifp, leaf_lblk, &icur, &got) &&
            got.br_startoff == leaf_lblk &&
            got.br_blockcount == args.geo->fsbcount &&
            !xfs_iext_next_extent(ifp, &icur, &got)) {
                if (is_block) {
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
                        goto out;
                }
                error = xchk_directory_leaf1_bestfree(sc, &args,
                                leaf_lblk);
                if (error)
                        goto out;
        }

        if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                goto out;

        /* Scan for free blocks */
        lblk = free_lblk;
        found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
        while (found && !(sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)) {
                /*
                 * Dirs can't have blocks mapped above 2^32.
                 * Single-block dirs shouldn't even be here.
                 */
                lblk = got.br_startoff;
                if (lblk & ~0xFFFFFFFFULL) {
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
                        goto out;
                }
                if (is_block) {
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
                        goto out;
                }

                /*
                 * Check each dir free block's bestfree data.
                 *
                 * Iterate all the fsbcount-aligned block offsets in
                 * this directory.  The directory block reading code is
                 * smart enough to do its own bmap lookups to handle
                 * discontiguous directory blocks.  When we're done
                 * with the extent record, re-query the bmap at the
                 * next fsbcount-aligned offset to avoid redundant
                 * block checks.
                 */
                for (lblk = roundup((xfs_dablk_t)got.br_startoff,
                                args.geo->fsbcount);
                     lblk < got.br_startoff + got.br_blockcount;
                     lblk += args.geo->fsbcount) {
                        error = xchk_directory_free_bestfree(sc, &args,
                                        lblk);
                        if (error)
                                goto out;
                }
                dabno = got.br_startoff + got.br_blockcount;
                lblk = roundup(dabno, args.geo->fsbcount);
                found = xfs_iext_lookup_extent(sc->ip, ifp, lblk, &icur, &got);
        }
out:
        return error;
}

/* Scrub a whole directory. */
int
xchk_directory(
        struct xfs_scrub        *sc)
{
        struct xchk_dir_ctx     sdc = {
                .dir_iter.actor = xchk_dir_actor,
                .dir_iter.pos = 0,
                .sc = sc,
        };
        size_t                  bufsize;
        loff_t                  oldpos;
        int                     error = 0;

        if (!S_ISDIR(VFS_I(sc->ip)->i_mode))
                return -ENOENT;

        /* Plausible size? */
        if (sc->ip->i_d.di_size < xfs_dir2_sf_hdr_size(0)) {
                xchk_ino_set_corrupt(sc, sc->ip->i_ino);
                goto out;
        }

        /* Check directory tree structure */
        error = xchk_da_btree(sc, XFS_DATA_FORK, xchk_dir_rec, NULL);
        if (error)
                return error;

        if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                return error;

        /* Check the freespace. */
        error = xchk_directory_blocks(sc);
        if (error)
                return error;

        if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                return error;

        /*
         * Check that every dirent we see can also be looked up by hash.
         * Userspace usually asks for a 32k buffer, so we will too.
         */
        bufsize = (size_t)min_t(loff_t, XFS_READDIR_BUFSIZE,
                        sc->ip->i_d.di_size);

        /*
         * Look up every name in this directory by hash.
         *
         * Use the xfs_readdir function to call xchk_dir_actor on
         * every directory entry in this directory.  In _actor, we check
         * the name, inode number, and ftype (if applicable) of the
         * entry.  xfs_readdir uses the VFS filldir functions to provide
         * iteration context.
         *
         * The VFS grabs a read or write lock via i_rwsem before it reads
         * or writes to a directory.  If we've gotten this far we've
         * already obtained IOLOCK_EXCL, which (since 4.10) is the same as
         * getting a write lock on i_rwsem.  Therefore, it is safe for us
         * to drop the ILOCK here in order to reuse the _readdir and
         * _dir_lookup routines, which do their own ILOCK locking.
         */
        oldpos = 0;
        sc->ilock_flags &= ~XFS_ILOCK_EXCL;
        xfs_iunlock(sc->ip, XFS_ILOCK_EXCL);
        while (true) {
                error = xfs_readdir(sc->tp, sc->ip, &sdc.dir_iter, bufsize);
                if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, 0,
                                &error))
                        goto out;
                if (oldpos == sdc.dir_iter.pos)
                        break;
                oldpos = sdc.dir_iter.pos;
        }

out:
        return error;
}