// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2017-2023 Oracle.  All Rights Reserved.
 * Author: Darrick J. Wong <djwong@kernel.org>
 */
#include "xfs_platform.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 "xfs_health.h"
#include "xfs_attr.h"
#include "xfs_parent.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/dabtree.h"
#include "scrub/readdir.h"
#include "scrub/health.h"
#include "scrub/repair.h"
#include "scrub/trace.h"
#include "scrub/xfile.h"
#include "scrub/xfarray.h"
#include "scrub/xfblob.h"

/* Set us up to scrub directories. */
int
xchk_setup_directory(
        struct xfs_scrub        *sc)
{
        int                     error;

        if (xchk_could_repair(sc)) {
                error = xrep_setup_directory(sc);
                if (error)
                        return error;
        }

        return xchk_setup_inode_contents(sc, 0);
}

/* Directories */

/* Deferred directory entry that we saved for later. */
struct xchk_dirent {
        /* Cookie for retrieval of the dirent name. */
        xfblob_cookie           name_cookie;

        /* Child inode number. */
        xfs_ino_t               ino;

        /* Length of the pptr name. */
        uint8_t                 namelen;
};

struct xchk_dir {
        struct xfs_scrub        *sc;

        /* information for parent pointer validation. */
        struct xfs_parent_rec   pptr_rec;
        struct xfs_da_args      pptr_args;

        /* Fixed-size array of xchk_dirent structures. */
        struct xfarray          *dir_entries;

        /* Blobs containing dirent names. */
        struct xfblob           *dir_names;

        /* If we've cycled the ILOCK, we must revalidate deferred dirents. */
        bool                    need_revalidate;

        /* Name buffer for dirent revalidation. */
        struct xfs_name         xname;
        uint8_t                 namebuf[MAXNAMELEN];
};

/* Scrub a directory entry. */

/* Check that an inode's mode matches a given XFS_DIR3_FT_* type. */
STATIC void
xchk_dir_check_ftype(
        struct xfs_scrub        *sc,
        xfs_fileoff_t           offset,
        struct xfs_inode        *ip,
        int                     ftype)
{
        struct xfs_mount        *mp = sc->mp;

        if (!xfs_has_ftype(mp)) {
                if (ftype != XFS_DIR3_FT_UNKNOWN && ftype != XFS_DIR3_FT_DIR)
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, offset);
                return;
        }

        if (xfs_mode_to_ftype(VFS_I(ip)->i_mode) != ftype)
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, offset);

        /*
         * Metadata and regular inodes cannot cross trees.  This property
         * cannot change without a full inode free and realloc cycle, so it's
         * safe to check this without holding locks.
         */
        if (xfs_is_metadir_inode(ip) != xfs_is_metadir_inode(sc->ip))
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, offset);
}

/*
 * Try to lock a child file for checking parent pointers.  Returns the inode
 * flags for the locks we now hold, or zero if we failed.
 */
STATIC unsigned int
xchk_dir_lock_child(
        struct xfs_scrub        *sc,
        struct xfs_inode        *ip)
{
        if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED))
                return 0;

        if (!xfs_ilock_nowait(ip, XFS_ILOCK_SHARED)) {
                xfs_iunlock(ip, XFS_IOLOCK_SHARED);
                return 0;
        }

        if (!xfs_inode_has_attr_fork(ip) || !xfs_need_iread_extents(&ip->i_af))
                return XFS_IOLOCK_SHARED | XFS_ILOCK_SHARED;

        xfs_iunlock(ip, XFS_ILOCK_SHARED);

        if (!xfs_ilock_nowait(ip, XFS_ILOCK_EXCL)) {
                xfs_iunlock(ip, XFS_IOLOCK_SHARED);
                return 0;
        }

        return XFS_IOLOCK_SHARED | XFS_ILOCK_EXCL;
}

/* Check the backwards link (parent pointer) associated with this dirent. */
STATIC int
xchk_dir_parent_pointer(
        struct xchk_dir         *sd,
        const struct xfs_name   *name,
        struct xfs_inode        *ip)
{
        struct xfs_scrub        *sc = sd->sc;
        int                     error;

        xfs_inode_to_parent_rec(&sd->pptr_rec, sc->ip);
        error = xfs_parent_lookup(sc->tp, ip, name, &sd->pptr_rec,
                        &sd->pptr_args);
        if (error == -ENOATTR)
                xchk_fblock_xref_set_corrupt(sc, XFS_DATA_FORK, 0);

        return 0;
}

/* Look for a parent pointer matching this dirent, if the child isn't busy. */
STATIC int
xchk_dir_check_pptr_fast(
        struct xchk_dir         *sd,
        xfs_dir2_dataptr_t      dapos,
        const struct xfs_name   *name,
        struct xfs_inode        *ip)
{
        struct xfs_scrub        *sc = sd->sc;
        unsigned int            lockmode;
        int                     error;

        /* dot and dotdot entries do not have parent pointers */
        if (xfs_dir2_samename(name, &xfs_name_dot) ||
            xfs_dir2_samename(name, &xfs_name_dotdot))
                return 0;

        /* No self-referential non-dot or dotdot dirents. */
        if (ip == sc->ip) {
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);
                return -ECANCELED;
        }

        /* Try to lock the inode. */
        lockmode = xchk_dir_lock_child(sc, ip);
        if (!lockmode) {
                struct xchk_dirent      save_de = {
                        .namelen        = name->len,
                        .ino            = ip->i_ino,
                };

                /* Couldn't lock the inode, so save the dirent for later. */
                trace_xchk_dir_defer(sc->ip, name, ip->i_ino);

                error = xfblob_storename(sd->dir_names, &save_de.name_cookie,
                                name);
                if (!xchk_fblock_xref_process_error(sc, XFS_DATA_FORK, 0,
                                        &error))
                        return error;

                error = xfarray_append(sd->dir_entries, &save_de);
                if (!xchk_fblock_xref_process_error(sc, XFS_DATA_FORK, 0,
                                        &error))
                        return error;

                return 0;
        }

        error = xchk_dir_parent_pointer(sd, name, ip);
        xfs_iunlock(ip, lockmode);
        return error;
}

/*
 * Scrub a single directory entry.
 *
 * 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 xfs_scrub        *sc,
        struct xfs_inode        *dp,
        xfs_dir2_dataptr_t      dapos,
        const struct xfs_name   *name,
        xfs_ino_t               ino,
        void                    *priv)
{
        struct xfs_mount        *mp = dp->i_mount;
        struct xfs_inode        *ip;
        struct xchk_dir         *sd = priv;
        xfs_ino_t               lookup_ino;
        xfs_dablk_t             offset;
        int                     error = 0;

        offset = xfs_dir2_db_to_da(mp->m_dir_geo,
                        xfs_dir2_dataptr_to_db(mp->m_dir_geo, dapos));

        if (xchk_should_terminate(sc, &error))
                return error;

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

        /* Does this name make sense? */
        if (!xfs_dir2_namecheck(name->name, name->len)) {
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, offset);
                return -ECANCELED;
        }

        if (xfs_dir2_samename(name, &xfs_name_dot)) {
                /* If this is "." then check that the inum matches the dir. */
                if (ino != dp->i_ino)
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, offset);
        } else if (xfs_dir2_samename(name, &xfs_name_dotdot)) {
                /*
                 * If this is ".." in the root inode, check that the inum
                 * matches this dir.
                 */
                if (xchk_inode_is_dirtree_root(dp) && ino != dp->i_ino)
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, offset);
        }

        /* Verify that we can look up this name by hash. */
        error = xchk_dir_lookup(sc, dp, name, &lookup_ino);
        /* ENOENT means the hash lookup failed and the dir is corrupt */
        if (error == -ENOENT)
                error = -EFSCORRUPTED;
        if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, offset, &error))
                goto out;
        if (lookup_ino != ino) {
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, offset);
                return -ECANCELED;
        }

        /*
         * Grab the inode pointed to by the dirent.  We release the inode
         * before we cancel the scrub transaction.
         *
         * If _iget returns -EINVAL or -ENOENT then the child inode number is
         * garbage and the directory is corrupt.  If the _iget returns
         * -EFSCORRUPTED or -EFSBADCRC then the child is corrupt which is a
         *  cross referencing error.  Any other error is an operational error.
         */
        error = xchk_iget(sc, ino, &ip);
        if (error == -EINVAL || error == -ENOENT) {
                error = -EFSCORRUPTED;
                xchk_fblock_process_error(sc, XFS_DATA_FORK, 0, &error);
                goto out;
        }
        if (!xchk_fblock_xref_process_error(sc, XFS_DATA_FORK, offset, &error))
                goto out;

        xchk_dir_check_ftype(sc, offset, ip, name->type);

        if (xfs_has_parent(mp)) {
                error = xchk_dir_check_pptr_fast(sd, dapos, name, ip);
                if (error)
                        goto out_rele;
        }

out_rele:
        xchk_irele(sc, ip);
out:
        if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                return -ECANCELED;
        return error;
}

/* Scrub a directory btree record. */
STATIC int
xchk_dir_rec(
        struct xchk_da_btree            *ds,
        int                             level)
{
        struct xfs_name                 dname = { };
        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, ds->dargs.owner,
                        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;
        }

        /* Does the directory hash match? */
        dname.name = dent->name;
        dname.len = dent->namelen;
        calc_hash = xfs_dir2_hashname(mp, &dname);
        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, sc->ip->i_ino, &bp);
        } else {
                /* dir data format */
                error = xfs_dir3_data_read(sc->tp, sc->ip, sc->ip->i_ino, 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_dir2_db_t                   last_data_db,
        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, sc->ip->i_ino, 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_has_crc(sc->mp)) {
                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 must be enough bestfree slots to cover all the directory data
         * blocks that we scanned.  It is possible for there to be a hole
         * between the last data block and i_disk_size.  This seems like an
         * oversight to the scrub author, but as we have been writing out
         * directories like this (and xfs_repair doesn't mind them) for years,
         * that's what we have to check.
         */
        if (bestcount != last_data_db + 1) {
                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);
                error = xfs_dir3_data_read(sc->tp, sc->ip, args->owner,
                                xfs_dir2_db_to_da(args->geo, i),
                                XFS_DABUF_MAP_HOLE_OK, &dbp);
                if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, lblk,
                                &error))
                        break;

                if (!dbp) {
                        if (best != NULLDATAOFF) {
                                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK,
                                                lblk);
                                break;
                        }
                        continue;
                }

                if (best == NULLDATAOFF)
                        xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, lblk);
                else
                        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, sc->ip->i_ino, lblk, &bp);
        if (!xchk_fblock_process_error(sc, XFS_DATA_FORK, lblk, &error))
                return error;
        xchk_buffer_recheck(sc, bp);

        if (xfs_has_crc(sc->mp)) {
                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, args->owner,
                                (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 = {
                .dp             = sc->ip,
                .whichfork      = XFS_DATA_FORK,
                .geo            = sc->mp->m_dir_geo,
                .trans          = sc->tp,
                .owner          = sc->ip->i_ino,
        };
        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;
        xfs_dir2_db_t           last_data_db = 0;
        bool                    found;
        bool                    is_block = false;
        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? */
        if (xfs_dir2_format(&args, &error) == XFS_DIR2_FMT_BLOCK)
                is_block = true;
        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)) {
                /* 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) {
                        last_data_db = xfs_dir2_da_to_db(args.geo, lblk);
                        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, last_data_db,
                                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;
}

/*
 * Revalidate a dirent that we collected in the past but couldn't check because
 * of lock contention.  Returns 0 if the dirent is still valid, -ENOENT if it
 * has gone away on us, or a negative errno.
 */
STATIC int
xchk_dir_revalidate_dirent(
        struct xchk_dir         *sd,
        const struct xfs_name   *xname,
        xfs_ino_t               ino)
{
        struct xfs_scrub        *sc = sd->sc;
        xfs_ino_t               child_ino;
        int                     error;

        /*
         * Look up the directory entry.  If we get -ENOENT, the directory entry
         * went away and there's nothing to revalidate.  Return any other
         * error.
         */
        error = xchk_dir_lookup(sc, sc->ip, xname, &child_ino);
        if (error)
                return error;

        /* The inode number changed, nothing to revalidate. */
        if (ino != child_ino)
                return -ENOENT;

        return 0;
}

/*
 * Check a directory entry's parent pointers the slow way, which means we cycle
 * locks a bunch and put up with revalidation until we get it done.
 */
STATIC int
xchk_dir_slow_dirent(
        struct xchk_dir         *sd,
        struct xchk_dirent      *dirent,
        const struct xfs_name   *xname)
{
        struct xfs_scrub        *sc = sd->sc;
        struct xfs_inode        *ip;
        unsigned int            lockmode;
        int                     error;

        /* Check that the deferred dirent still exists. */
        if (sd->need_revalidate) {
                error = xchk_dir_revalidate_dirent(sd, xname, dirent->ino);
                if (error == -ENOENT)
                        return 0;
                if (!xchk_fblock_xref_process_error(sc, XFS_DATA_FORK, 0,
                                        &error))
                        return error;
        }

        error = xchk_iget(sc, dirent->ino, &ip);
        if (error == -EINVAL || error == -ENOENT) {
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);
                return 0;
        }
        if (!xchk_fblock_xref_process_error(sc, XFS_DATA_FORK, 0, &error))
                return error;

        /*
         * If we can grab both IOLOCK and ILOCK of the alleged child, we can
         * proceed with the validation.
         */
        lockmode = xchk_dir_lock_child(sc, ip);
        if (lockmode) {
                trace_xchk_dir_slowpath(sc->ip, xname, ip->i_ino);
                goto check_pptr;
        }

        /*
         * We couldn't lock the child file.  Drop all the locks and try to
         * get them again, one at a time.
         */
        xchk_iunlock(sc, sc->ilock_flags);
        sd->need_revalidate = true;

        trace_xchk_dir_ultraslowpath(sc->ip, xname, ip->i_ino);

        error = xchk_dir_trylock_for_pptrs(sc, ip, &lockmode);
        if (error)
                goto out_rele;

        /* Revalidate, since we just cycled the locks. */
        error = xchk_dir_revalidate_dirent(sd, xname, dirent->ino);
        if (error == -ENOENT) {
                error = 0;
                goto out_unlock;
        }
        if (!xchk_fblock_xref_process_error(sc, XFS_DATA_FORK, 0, &error))
                goto out_unlock;

check_pptr:
        error = xchk_dir_parent_pointer(sd, xname, ip);
out_unlock:
        xfs_iunlock(ip, lockmode);
out_rele:
        xchk_irele(sc, ip);
        return error;
}

/* Check all the dirents that we deferred the first time around. */
STATIC int
xchk_dir_finish_slow_dirents(
        struct xchk_dir         *sd)
{
        xfarray_idx_t           array_cur;
        int                     error;

        foreach_xfarray_idx(sd->dir_entries, array_cur) {
                struct xchk_dirent      dirent;

                if (sd->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                        return 0;

                error = xfarray_load(sd->dir_entries, array_cur, &dirent);
                if (error)
                        return error;

                error = xfblob_loadname(sd->dir_names, dirent.name_cookie,
                                &sd->xname, dirent.namelen);
                if (error)
                        return error;

                error = xchk_dir_slow_dirent(sd, &dirent, &sd->xname);
                if (error)
                        return error;
        }

        return 0;
}

/* Scrub a whole directory. */
int
xchk_directory(
        struct xfs_scrub        *sc)
{
        struct xchk_dir         *sd;
        int                     error;

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

        if (xchk_file_looks_zapped(sc, XFS_SICK_INO_DIR_ZAPPED)) {
                xchk_fblock_set_corrupt(sc, XFS_DATA_FORK, 0);
                return 0;
        }

        /* Plausible size? */
        if (sc->ip->i_disk_size < xfs_dir2_sf_hdr_size(0)) {
                xchk_ino_set_corrupt(sc, sc->ip->i_ino);
                return 0;
        }

        /* 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 0;

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

        if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
                return 0;

        sd = kvzalloc_obj(struct xchk_dir, XCHK_GFP_FLAGS);
        if (!sd)
                return -ENOMEM;
        sd->sc = sc;
        sd->xname.name = sd->namebuf;

        if (xfs_has_parent(sc->mp)) {
                /*
                 * Set up some staging memory for dirents that we can't check
                 * due to locking contention.
                 */
                error = xfarray_create("slow directory entries", 0,
                                sizeof(struct xchk_dirent), &sd->dir_entries);
                if (error)
                        goto out_sd;

                error = xfblob_create("slow directory entry names",
                                &sd->dir_names);
                if (error)
                        goto out_entries;
        }

        /* Look up every name in this directory by hash. */
        error = xchk_dir_walk(sc, sc->ip, xchk_dir_actor, sd);
        if (error == -ECANCELED)
                error = 0;
        if (error)
                goto out_names;

        if (xfs_has_parent(sc->mp)) {
                error = xchk_dir_finish_slow_dirents(sd);
                if (error == -ETIMEDOUT) {
                        /* Couldn't grab a lock, scrub was marked incomplete */
                        error = 0;
                        goto out_names;
                }
                if (error)
                        goto out_names;
        }

out_names:
        if (sd->dir_names)
                xfblob_destroy(sd->dir_names);
out_entries:
        if (sd->dir_entries)
                xfarray_destroy(sd->dir_entries);
out_sd:
        kvfree(sd);
        if (error)
                return error;

        /* If the dir is clean, it is clearly not zapped. */
        xchk_mark_healthy_if_clean(sc, XFS_SICK_INO_DIR_ZAPPED);
        return 0;
}

/*
 * Decide if this directory has been zapped to satisfy the inode and ifork
 * verifiers.  Checking and repairing should be postponed until the directory
 * is fixed.
 */
bool
xchk_dir_looks_zapped(
        struct xfs_inode        *dp)
{
        /* Repair zapped this dir's data fork a short time ago */
        if (xfs_ifork_zapped(dp, XFS_DATA_FORK))
                return true;

        /*
         * If the dinode repair found a bad data fork, it will reset the fork
         * to extents format with zero records and wait for the bmapbtd
         * scrubber to reconstruct the block mappings.  Directories always
         * contain some content, so this is a clear sign of a zapped directory.
         * The state checked by xfs_ifork_zapped is not persisted, so this is
         * the secondary strategy if repairs are interrupted by a crash or an
         * unmount.
         */
        return dp->i_df.if_format == XFS_DINODE_FMT_EXTENTS &&
               dp->i_df.if_nextents == 0;
}