/*      $NetBSD: msdosfs_denode.c,v 1.60 2021/10/23 16:58:17 thorpej Exp $      */

/*-
 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
 * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
 * All rights reserved.
 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by TooLs GmbH.
 * 4. The name of TooLs GmbH may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/*
 * Written by Paul Popelka (paulp@uts.amdahl.com)
 *
 * You can do anything you want with this software, just don't say you wrote
 * it, and don't remove this notice.
 *
 * This software is provided "as is".
 *
 * The author supplies this software to be publicly redistributed on the
 * understanding that the author is not responsible for the correct
 * functioning of this software in any circumstances and is not liable for
 * any damages caused by this software.
 *
 * October 1992
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: msdosfs_denode.c,v 1.60 2021/10/23 16:58:17 thorpej Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mount.h>
#include <sys/malloc.h>
#include <sys/pool.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/vnode.h>
#include <sys/kernel.h>         /* defines "time" */
#include <sys/dirent.h>
#include <sys/namei.h>
#include <sys/kauth.h>

#include <uvm/uvm_extern.h>

#include <fs/msdosfs/bpb.h>
#include <fs/msdosfs/msdosfsmount.h>
#include <fs/msdosfs/direntry.h>
#include <fs/msdosfs/denode.h>
#include <fs/msdosfs/fat.h>

struct pool msdosfs_denode_pool;

struct fh_key {
        struct msdosfsmount *fhk_mount;
        uint32_t fhk_dircluster;
        uint32_t fhk_diroffset;
};
struct fh_node {
        struct rb_node fh_rbnode;
        struct fh_key fh_key;
#define fh_mount        fh_key.fhk_mount
#define fh_dircluster   fh_key.fhk_dircluster
#define fh_diroffset    fh_key.fhk_diroffset
        uint32_t fh_gen;
};

static int
fh_compare_node_fh(void *ctx, const void *b, const void *key)
{
        const struct fh_node * const pnp = b;
        const struct fh_key * const fhp = key;

        /* msdosfs_fh_destroy() below depends on first sorting on fh_mount. */
        if (pnp->fh_mount != fhp->fhk_mount)
                return (intptr_t)pnp->fh_mount - (intptr_t)fhp->fhk_mount;
        if (pnp->fh_dircluster != fhp->fhk_dircluster)
                return pnp->fh_dircluster - fhp->fhk_dircluster;
        return pnp->fh_diroffset - fhp->fhk_diroffset;
}

static int
fh_compare_nodes(void *ctx, const void *parent, const void *node)
{
        const struct fh_node * const np = node;

        return fh_compare_node_fh(ctx, parent, &np->fh_key);
}

static uint32_t fh_generation;
static kmutex_t fh_lock;
static struct pool fh_pool;
static rb_tree_t fh_rbtree;
static const rb_tree_ops_t fh_rbtree_ops = {
        .rbto_compare_nodes = fh_compare_nodes,
        .rbto_compare_key = fh_compare_node_fh,
        .rbto_node_offset = offsetof(struct fh_node, fh_rbnode),
        .rbto_context = NULL
};

static const struct genfs_ops msdosfs_genfsops = {
        .gop_size = genfs_size,
        .gop_alloc = msdosfs_gop_alloc,
        .gop_write = genfs_gop_write,
        .gop_markupdate = msdosfs_gop_markupdate,
        .gop_putrange = genfs_gop_putrange,
};

MALLOC_DECLARE(M_MSDOSFSFAT);

void
msdosfs_init(void)
{

        malloc_type_attach(M_MSDOSFSMNT);
        malloc_type_attach(M_MSDOSFSFAT);
        malloc_type_attach(M_MSDOSFSTMP);
        pool_init(&msdosfs_denode_pool, sizeof(struct denode), 0, 0, 0,
            "msdosnopl", &pool_allocator_nointr, IPL_NONE);
        pool_init(&fh_pool, sizeof(struct fh_node), 0, 0, 0,
            "msdosfhpl", &pool_allocator_nointr, IPL_NONE);
        rb_tree_init(&fh_rbtree, &fh_rbtree_ops);
        mutex_init(&fh_lock, MUTEX_DEFAULT, IPL_NONE);
}

/*
 * Reinitialize.
 */

void
msdosfs_reinit(void)
{

}

void
msdosfs_done(void)
{
        pool_destroy(&msdosfs_denode_pool);
        pool_destroy(&fh_pool);
        mutex_destroy(&fh_lock);
        malloc_type_detach(M_MSDOSFSTMP);
        malloc_type_detach(M_MSDOSFSFAT);
        malloc_type_detach(M_MSDOSFSMNT);
}

/*
 * If deget() succeeds it returns with the gotten denode unlocked.
 *
 * pmp       - address of msdosfsmount structure of the filesystem containing
 *             the denode of interest.  The pm_dev field and the address of
 *             the msdosfsmount structure are used.
 * dirclust  - which cluster bp contains, if dirclust is 0 (root directory)
 *             diroffset is relative to the beginning of the root directory,
 *             otherwise it is cluster relative.
 * diroffset - offset past begin of cluster of denode we want
 * vpp       - returns the address of the gotten vnode.
 */
int
msdosfs_deget(struct msdosfsmount *pmp, u_long dirclust, u_long diroffset,
    struct vnode **vpp)
        /* pmp:  so we know the maj/min number */
        /* dirclust:             cluster this dir entry came from */
        /* diroffset:            index of entry within the cluster */
        /* vpp:                  returns the addr of the gotten vnode */
{
        int error;
        struct denode_key key;

        /*
         * On FAT32 filesystems, root is a (more or less) normal
         * directory
         */
        if (FAT32(pmp) && dirclust == MSDOSFSROOT)
                dirclust = pmp->pm_rootdirblk;

        memset(&key, 0, sizeof(key));
        key.dk_dirclust = dirclust;
        key.dk_diroffset = diroffset;
        /* key.dk_dirgen = NULL; */

        error = vcache_get(pmp->pm_mountp, &key, sizeof(key), vpp);
        return error;
}

int
msdosfs_loadvnode(struct mount *mp, struct vnode *vp,
    const void *key, size_t key_len, const void **new_key)
{
        bool is_root;
        int error;
        extern int (**msdosfs_vnodeop_p)(void *);
        struct msdosfsmount *pmp;
        struct direntry *direntptr;
        struct denode *ldep;
        struct buf *bp;
        struct denode_key dkey;

        KASSERT(key_len == sizeof(dkey));
        memcpy(&dkey, key, key_len);
        KASSERT(dkey.dk_dirgen == NULL);

        pmp = VFSTOMSDOSFS(mp);
        is_root = ((dkey.dk_dirclust == MSDOSFSROOT ||
            (FAT32(pmp) && dkey.dk_dirclust == pmp->pm_rootdirblk)) &&
            dkey.dk_diroffset == MSDOSFSROOT_OFS);

#ifdef MSDOSFS_DEBUG
        printf("loadvnode(pmp %p, dirclust %lu, diroffset %lx, vp %p)\n",
            pmp, dkey.dk_dirclust, dkey.dk_diroffset, vp);
#endif

        ldep = pool_get(&msdosfs_denode_pool, PR_WAITOK);
        memset(ldep, 0, sizeof *ldep);
        /* ldep->de_flag = 0; */
        /* ldep->de_devvp = 0; */
        /* ldep->de_lockf = 0; */
        ldep->de_dev = pmp->pm_dev;
        ldep->de_dirclust = dkey.dk_dirclust;
        ldep->de_diroffset = dkey.dk_diroffset;
        ldep->de_pmp = pmp;
        ldep->de_devvp = pmp->pm_devvp;
        ldep->de_refcnt = 1;
        msdosfs_fc_purge(ldep, 0);      /* init the FAT cache for this denode */

        /*
         * Copy the directory entry into the denode area of the vnode.
         */
        if (is_root) {
                /*
                 * Directory entry for the root directory. There isn't one,
                 * so we manufacture one. We should probably rummage
                 * through the root directory and find a label entry (if it
                 * exists), and then use the time and date from that entry
                 * as the time and date for the root denode.
                 */
                ldep->de_Attributes = ATTR_DIRECTORY;
                if (FAT32(pmp))
                        ldep->de_StartCluster = pmp->pm_rootdirblk;
                        /* de_FileSize will be filled in further down */
                else {
                        ldep->de_StartCluster = MSDOSFSROOT;
                        ldep->de_FileSize = pmp->pm_rootdirsize *
                            pmp->pm_BytesPerSec;
                }
                /*
                 * fill in time and date so that dos2unixtime() doesn't
                 * spit up when called from msdosfs_getattr() with root
                 * denode
                 */
                ldep->de_CHun = 0;
                ldep->de_CTime = 0x0000;        /* 00:00:00      */
                ldep->de_CDate = (0 << DD_YEAR_SHIFT) | (1 << DD_MONTH_SHIFT)
                    | (1 << DD_DAY_SHIFT);
                /* Jan 1, 1980   */
                ldep->de_ADate = ldep->de_CDate;
                ldep->de_MTime = ldep->de_CTime;
                ldep->de_MDate = ldep->de_CDate;
                /* leave the other fields as garbage */
        } else {
                error = msdosfs_readep(pmp, ldep->de_dirclust,
                    ldep->de_diroffset, &bp, &direntptr);
                if (error) {
                        pool_put(&msdosfs_denode_pool, ldep);
                        return error;
                }
                DE_INTERNALIZE(ldep, direntptr);
                brelse(bp, 0);
        }

        /*
         * Fill in a few fields of the vnode and finish filling in the
         * denode.
         */
        if (ldep->de_Attributes & ATTR_DIRECTORY) {
                /*
                 * Since DOS directory entries that describe directories
                 * have 0 in the filesize field, we take this opportunity
                 * to find out the length of the directory and plug it into
                 * the denode structure.
                 */
                u_long size;

                vp->v_type = VDIR;
                if (ldep->de_StartCluster != MSDOSFSROOT) {
                        error = msdosfs_pcbmap(ldep, CLUST_END, 0, &size, 0);
                        if (error == E2BIG) {
                                ldep->de_FileSize = de_cn2off(pmp, size);
                                error = 0;
                        } else
                                printf("loadvnode(): pcbmap returned %d\n",
                                    error);
                }
        } else
                vp->v_type = VREG;
        vref(ldep->de_devvp);
        if (is_root)
                vp->v_vflag |= VV_ROOT;
        vp->v_tag = VT_MSDOSFS;
        vp->v_op = msdosfs_vnodeop_p;
        vp->v_data = ldep;
        ldep->de_vnode = vp;
        genfs_node_init(vp, &msdosfs_genfsops);
        uvm_vnp_setsize(vp, ldep->de_FileSize);
        *new_key = &ldep->de_key;

        return 0;
}

int
msdosfs_deupdat(struct denode *dep, int waitfor)
{

        return (msdosfs_update(DETOV(dep), NULL, NULL,
            waitfor ? UPDATE_WAIT : 0));
}

/*
 * Truncate the file described by dep to the length specified by length.
 */
int
msdosfs_detrunc(struct denode *dep, u_long length, int flags, kauth_cred_t cred)
{
        int error;
        int allerror;
        u_long eofentry;
        u_long chaintofree = 0;
        daddr_t bn, lastblock;
        int boff;
        int isadir = dep->de_Attributes & ATTR_DIRECTORY;
        struct buf *bp;
        struct msdosfsmount *pmp = dep->de_pmp;

#ifdef MSDOSFS_DEBUG
        printf("detrunc(): file %s, length %lu, flags %x\n", dep->de_Name, length, flags);
#endif

        /*
         * Disallow attempts to truncate the root directory since it is of
         * fixed size.  That's just the way dos filesystems are.  We use
         * the VROOT bit in the vnode because checking for the directory
         * bit and a startcluster of 0 in the denode is not adequate to
         * recognize the root directory at this point in a file or
         * directory's life.
         */
        if ((DETOV(dep)->v_vflag & VV_ROOT) && !FAT32(pmp)) {
                printf("detrunc(): can't truncate root directory, clust %ld, offset %ld\n",
                    dep->de_dirclust, dep->de_diroffset);
                return (EINVAL);
        }

        uvm_vnp_setsize(DETOV(dep), length);

        if (dep->de_FileSize < length)
                return (msdosfs_deextend(dep, length, cred));
        lastblock = de_clcount(pmp, length) - 1;

        /*
         * If the desired length is 0 then remember the starting cluster of
         * the file and set the StartCluster field in the directory entry
         * to 0.  If the desired length is not zero, then get the number of
         * the last cluster in the shortened file.  Then get the number of
         * the first cluster in the part of the file that is to be freed.
         * Then set the next cluster pointer in the last cluster of the
         * file to CLUST_EOFE.
         */
        if (length == 0) {
                chaintofree = dep->de_StartCluster;
                dep->de_StartCluster = 0;
                eofentry = ~0;
        } else {
                error = msdosfs_pcbmap(dep, lastblock, 0, &eofentry, 0);
                if (error) {
#ifdef MSDOSFS_DEBUG
                        printf("detrunc(): pcbmap fails %d\n", error);
#endif
                        return (error);
                }
        }

        /*
         * If the new length is not a multiple of the cluster size then we
         * must zero the tail end of the new last cluster in case it
         * becomes part of the file again because of a seek.
         */
        if ((boff = length & pmp->pm_crbomask) != 0) {
                if (isadir) {
                        bn = cntobn(pmp, eofentry);
                        error = bread(pmp->pm_devvp, de_bn2kb(pmp, bn),
                            pmp->pm_bpcluster, B_MODIFY, &bp);
                        if (error) {
#ifdef MSDOSFS_DEBUG
                                printf("detrunc(): bread fails %d\n", error);
#endif
                                return (error);
                        }
                        memset((char *)bp->b_data + boff, 0,
                            pmp->pm_bpcluster - boff);
                        if (flags & IO_SYNC)
                                bwrite(bp);
                        else
                                bdwrite(bp);
                } else {
                        ubc_zerorange(&DETOV(dep)->v_uobj, length,
                                      pmp->pm_bpcluster - boff,
                                      UBC_VNODE_FLAGS(DETOV(dep)));
                }
        }

        /*
         * Write out the updated directory entry.  Even if the update fails
         * we free the trailing clusters.
         */
        dep->de_FileSize = length;
        if (!isadir)
                dep->de_flag |= DE_UPDATE|DE_MODIFIED;
        vtruncbuf(DETOV(dep), lastblock + 1, 0, 0);
        allerror = msdosfs_deupdat(dep, 1);
#ifdef MSDOSFS_DEBUG
        printf("detrunc(): allerror %d, eofentry %lu\n",
               allerror, eofentry);
#endif

        msdosfs_fc_purge(dep, lastblock + 1);

        /*
         * If we need to break the cluster chain for the file then do it
         * now.
         */
        if (eofentry != ~0) {
                error = msdosfs_fatentry(FAT_GET_AND_SET, pmp, eofentry,
                                 &chaintofree, CLUST_EOFE);
                if (error) {
#ifdef MSDOSFS_DEBUG
                        printf("detrunc(): fatentry errors %d\n", error);
#endif
                        return (error);
                }
                fc_setcache(dep, FC_LASTFC, de_cluster(pmp, length - 1),
                            eofentry);
        }

        /*
         * Now free the clusters removed from the file because of the
         * truncation.
         */
        if (chaintofree != 0 && !MSDOSFSEOF(chaintofree, pmp->pm_fatmask))
                msdosfs_freeclusterchain(pmp, chaintofree);

        return (allerror);
}

/*
 * Extend the file described by dep to length specified by length.
 */
int
msdosfs_deextend(struct denode *dep, u_long length, kauth_cred_t cred)
{
        struct msdosfsmount *pmp = dep->de_pmp;
        u_long count, osize;
        int error;

        /*
         * The root of a DOS filesystem cannot be extended.
         */
        if ((DETOV(dep)->v_vflag & VV_ROOT) && !FAT32(pmp))
                return (EINVAL);

        /*
         * Directories cannot be extended.
         */
        if (dep->de_Attributes & ATTR_DIRECTORY)
                return (EISDIR);

        if (length <= dep->de_FileSize)
                panic("deextend: file too large");

        /*
         * Compute the number of clusters to allocate.
         */
        count = de_clcount(pmp, length) - de_clcount(pmp, dep->de_FileSize);
        if (count > 0) {
                if (count > pmp->pm_freeclustercount)
                        return (ENOSPC);
                error = msdosfs_extendfile(dep, count, NULL, NULL, DE_CLEAR);
                if (error) {
                        /* truncate the added clusters away again */
                        (void) msdosfs_detrunc(dep, dep->de_FileSize, 0, cred);
                        return (error);
                }
        }

        /*
         * Zero extend file range; ubc_zerorange() uses ubc_alloc() and a
         * memset(); we set the write size so ubc won't read in file data that
         * is zero'd later.
         */
        osize = dep->de_FileSize;
        dep->de_FileSize = length;
        uvm_vnp_setwritesize(DETOV(dep), (voff_t)dep->de_FileSize);
        dep->de_flag |= DE_UPDATE|DE_MODIFIED;
        ubc_zerorange(&DETOV(dep)->v_uobj, (off_t)osize,
            (size_t)(round_page(dep->de_FileSize) - osize),
            UBC_VNODE_FLAGS(DETOV(dep)));
        uvm_vnp_setsize(DETOV(dep), (voff_t)dep->de_FileSize);
        return (msdosfs_deupdat(dep, 1));
}

int
msdosfs_reclaim(void *v)
{
        struct vop_reclaim_v2_args /* {
                struct vnode *a_vp;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;
        struct denode *dep = VTODE(vp);

        VOP_UNLOCK(vp);

#ifdef MSDOSFS_DEBUG
        printf("msdosfs_reclaim(): dep %p, file %s, refcnt %ld\n",
            dep, dep->de_Name, dep->de_refcnt);
#endif

        /*
         * Purge old data structures associated with the denode.
         */
        if (dep->de_devvp) {
                vrele(dep->de_devvp);
                dep->de_devvp = 0;
        }
#if 0 /* XXX */
        dep->de_flag = 0;
#endif
        /*
         * To interlock with msdosfs_sync().
         */
        genfs_node_destroy(vp);
        mutex_enter(vp->v_interlock);
        vp->v_data = NULL;
        mutex_exit(vp->v_interlock);
        pool_put(&msdosfs_denode_pool, dep);
        return (0);
}

int
msdosfs_inactive(void *v)
{
        struct vop_inactive_v2_args /* {
                struct vnode *a_vp;
                bool *a_recycle;
        } */ *ap = v;
        struct vnode *vp = ap->a_vp;
        struct denode *dep = VTODE(vp);
        int error = 0;

#ifdef MSDOSFS_DEBUG
        printf("msdosfs_inactive(): dep %p, de_Name[0] %x\n", dep, dep->de_Name[0]);
#endif

        /*
         * Get rid of denodes related to stale file handles.
         */
        if (dep->de_Name[0] == SLOT_DELETED)
                goto out;

        /*
         * If the file has been deleted and it is on a read/write
         * filesystem, then truncate the file, and mark the directory slot
         * as empty.  (This may not be necessary for the dos filesystem.)
         */
#ifdef MSDOSFS_DEBUG
        printf("msdosfs_inactive(): dep %p, refcnt %ld, mntflag %x %s\n",
               dep, dep->de_refcnt, vp->v_mount->mnt_flag,
                (vp->v_mount->mnt_flag & MNT_RDONLY) ? "MNT_RDONLY" : "");
#endif
        if (dep->de_refcnt <= 0 && (vp->v_mount->mnt_flag & MNT_RDONLY) == 0) {
                if (dep->de_FileSize != 0) {
                        error = msdosfs_detrunc(dep, (u_long)0, 0, NOCRED);
                }
                dep->de_Name[0] = SLOT_DELETED;
                msdosfs_fh_remove(dep->de_pmp,
                    dep->de_dirclust, dep->de_diroffset);
        }
        msdosfs_deupdat(dep, 0);
out:
        /*
         * If we are done with the denode, reclaim it
         * so that it can be reused immediately.
         */
#ifdef MSDOSFS_DEBUG
        printf("msdosfs_inactive(): usecount %d, de_Name[0] %x\n",
                vrefcnt(vp), dep->de_Name[0]);
#endif
        *ap->a_recycle = (dep->de_Name[0] == SLOT_DELETED);

        return (error);
}

int
msdosfs_gop_alloc(struct vnode *vp, off_t off,
    off_t len, int flags, kauth_cred_t cred)
{
        return 0;
}

void
msdosfs_gop_markupdate(struct vnode *vp, int flags)
{
        u_long mask = 0;

        if ((flags & GOP_UPDATE_ACCESSED) != 0) {
                mask = DE_ACCESS;
        }
        if ((flags & GOP_UPDATE_MODIFIED) != 0) {
                mask |= DE_UPDATE;
        }
        if (mask) {
                struct denode *dep = VTODE(vp);

                dep->de_flag |= mask;
        }
}

int
msdosfs_fh_enter(struct msdosfsmount *pmp,
     uint32_t dircluster, uint32_t diroffset, uint32_t *genp)
{
        struct fh_key fhkey;
        struct fh_node *fhp;

        fhkey.fhk_mount = pmp;
        fhkey.fhk_dircluster = dircluster;
        fhkey.fhk_diroffset = diroffset;

        mutex_enter(&fh_lock);
        fhp = rb_tree_find_node(&fh_rbtree, &fhkey);
        if (fhp == NULL) {
                mutex_exit(&fh_lock);
                fhp = pool_get(&fh_pool, PR_WAITOK);
                mutex_enter(&fh_lock);
                fhp->fh_key = fhkey;
                fhp->fh_gen = fh_generation++;
                rb_tree_insert_node(&fh_rbtree, fhp);
        }
        *genp = fhp->fh_gen;
        mutex_exit(&fh_lock);
        return 0;
}

int
msdosfs_fh_remove(struct msdosfsmount *pmp,
     uint32_t dircluster, uint32_t diroffset)
{
        struct fh_key fhkey;
        struct fh_node *fhp;

        fhkey.fhk_mount = pmp;
        fhkey.fhk_dircluster = dircluster;
        fhkey.fhk_diroffset = diroffset;

        mutex_enter(&fh_lock);
        fhp = rb_tree_find_node(&fh_rbtree, &fhkey);
        if (fhp == NULL) {
                mutex_exit(&fh_lock);
                return ENOENT;
        }
        rb_tree_remove_node(&fh_rbtree, fhp);
        mutex_exit(&fh_lock);
        pool_put(&fh_pool, fhp);
        return 0;
}

int
msdosfs_fh_lookup(struct msdosfsmount *pmp,
     uint32_t dircluster, uint32_t diroffset, uint32_t *genp)
{
        struct fh_key fhkey;
        struct fh_node *fhp;

        fhkey.fhk_mount = pmp;
        fhkey.fhk_dircluster = dircluster;
        fhkey.fhk_diroffset = diroffset;

        mutex_enter(&fh_lock);
        fhp = rb_tree_find_node(&fh_rbtree, &fhkey);
        if (fhp == NULL) {
                mutex_exit(&fh_lock);
                return ESTALE;
        }
        *genp = fhp->fh_gen;
        mutex_exit(&fh_lock);
        return 0;
}

void
msdosfs_fh_destroy(struct msdosfsmount *pmp)
{
        struct fh_key fhkey;
        struct fh_node *fhp, *nfhp;

        fhkey.fhk_mount = pmp;
        fhkey.fhk_dircluster = 0;
        fhkey.fhk_diroffset = 0;

        mutex_enter(&fh_lock);
        for (fhp = rb_tree_find_node_geq(&fh_rbtree, &fhkey);
            fhp != NULL && fhp->fh_mount == pmp; fhp = nfhp) {
                nfhp = rb_tree_iterate(&fh_rbtree, fhp, RB_DIR_RIGHT);
                rb_tree_remove_node(&fh_rbtree, fhp);
                pool_put(&fh_pool, fhp);
        }
#ifdef DIAGNOSTIC
        RB_TREE_FOREACH(fhp, &fh_rbtree) {
                KASSERT(fhp->fh_mount != pmp);
        }
#endif
        mutex_exit(&fh_lock);
}