/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1982, 1986, 1990, 1993, 1995
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Robert Elz at The University of Melbourne.
 *
 * 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. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 THE REGENTS OR CONTRIBUTORS 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.
 */

#include <sys/cdefs.h>
#include "opt_ffs.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/endian.h>
#include <sys/fcntl.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/namei.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/vnode.h>

#include <ufs/ufs/extattr.h>
#include <ufs/ufs/quota.h>
#include <ufs/ufs/inode.h>
#include <ufs/ufs/ufsmount.h>
#include <ufs/ufs/ufs_extern.h>

CTASSERT(sizeof(struct dqblk64) == sizeof(struct dqhdr64));

static int unprivileged_get_quota = 0;
SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_get_quota, CTLFLAG_RW,
    &unprivileged_get_quota, 0,
    "Unprivileged processes may retrieve quotas for other uids and gids");

static MALLOC_DEFINE(M_DQUOT, "ufs_quota", "UFS quota entries");

/*
 * Quota name to error message mapping.
 */
static char *quotatypes[] = INITQFNAMES;

static int chkdqchg(struct inode *, ufs2_daddr_t, struct ucred *, int, int *);
static int chkiqchg(struct inode *, int, struct ucred *, int, int *);
static int dqopen(struct vnode *, struct ufsmount *, int);
static int dqget(struct vnode *,
        uint64_t, struct ufsmount *, int, struct dquot **);
static int dqsync(struct vnode *, struct dquot *);
static int dqflush(struct vnode *);
static int quotaoff1(struct thread *td, struct mount *mp, int type);
static int quotaoff_inchange(struct thread *td, struct mount *mp, int type);

/* conversion functions - from_to() */
static void dqb32_dq(const struct dqblk32 *, struct dquot *);
static void dqb64_dq(const struct dqblk64 *, struct dquot *);
static void dq_dqb32(const struct dquot *, struct dqblk32 *);
static void dq_dqb64(const struct dquot *, struct dqblk64 *);
static void dqb32_dqb64(const struct dqblk32 *, struct dqblk64 *);
static void dqb64_dqb32(const struct dqblk64 *, struct dqblk32 *);

#ifdef DIAGNOSTIC
static void dqref(struct dquot *);
static void chkdquot(struct inode *);
#endif

/*
 * Set up the quotas for an inode.
 *
 * This routine completely defines the semantics of quotas.
 * If other criterion want to be used to establish quotas, the
 * MAXQUOTAS value in quota.h should be increased, and the
 * additional dquots set up here.
 */
int
getinoquota(struct inode *ip)
{
        struct ufsmount *ump;
        struct vnode *vp;
        int error;

        vp = ITOV(ip);

        /*
         * Disk quotas must be turned off for system files.  Currently
         * snapshot and quota files.
         */
        if ((vp->v_vflag & VV_SYSTEM) != 0)
                return (0);
        /*
         * XXX: Turn off quotas for files with a negative UID or GID.
         * This prevents the creation of 100GB+ quota files.
         */
        if ((int)ip->i_uid < 0 || (int)ip->i_gid < 0)
                return (0);
        ump = VFSTOUFS(vp->v_mount);
        /*
         * Set up the user quota based on file uid.
         * EINVAL means that quotas are not enabled.
         */
        if ((error =
                dqget(vp, ip->i_uid, ump, USRQUOTA, &ip->i_dquot[USRQUOTA])) &&
            error != EINVAL)
                return (error);
        /*
         * Set up the group quota based on file gid.
         * EINVAL means that quotas are not enabled.
         */
        if ((error =
                dqget(vp, ip->i_gid, ump, GRPQUOTA, &ip->i_dquot[GRPQUOTA])) &&
            error != EINVAL)
                return (error);
        return (0);
}

/*
 * Update disk usage, and take corrective action.
 */
int
chkdq(struct inode *ip, ufs2_daddr_t change, struct ucred *cred, int flags)
{
        struct dquot *dq;
        ufs2_daddr_t ncurblocks;
        struct vnode *vp = ITOV(ip);
        int i, error, warn, do_check;

        MPASS(cred != NOCRED || (flags & FORCE) != 0);
        /*
         * Disk quotas must be turned off for system files.  Currently
         * snapshot and quota files.
         */
        if ((vp->v_vflag & VV_SYSTEM) != 0)
                return (0);
        /*
         * XXX: Turn off quotas for files with a negative UID or GID.
         * This prevents the creation of 100GB+ quota files.
         */
        if ((int)ip->i_uid < 0 || (int)ip->i_gid < 0)
                return (0);
#ifdef DIAGNOSTIC
        if ((flags & CHOWN) == 0)
                chkdquot(ip);
#endif
        if (change == 0)
                return (0);
        if (change < 0) {
                for (i = 0; i < MAXQUOTAS; i++) {
                        if ((dq = ip->i_dquot[i]) == NODQUOT)
                                continue;
                        DQI_LOCK(dq);
                        DQI_WAIT(dq, PINOD, "chkdq1");
                        ncurblocks = dq->dq_curblocks + change;
                        if (ncurblocks >= 0)
                                dq->dq_curblocks = ncurblocks;
                        else
                                dq->dq_curblocks = 0;
                        dq->dq_flags &= ~DQ_BLKS;
                        dq->dq_flags |= DQ_MOD;
                        DQI_UNLOCK(dq);
                }
                return (0);
        }
        if ((flags & FORCE) == 0 &&
            priv_check_cred(cred, PRIV_VFS_EXCEEDQUOTA))
                do_check = 1;
        else
                do_check = 0;
        for (i = 0; i < MAXQUOTAS; i++) {
                if ((dq = ip->i_dquot[i]) == NODQUOT)
                        continue;
                warn = 0;
                DQI_LOCK(dq);
                DQI_WAIT(dq, PINOD, "chkdq2");
                if (do_check) {
                        error = chkdqchg(ip, change, cred, i, &warn);
                        if (error) {
                                /*
                                 * Roll back user quota changes when
                                 * group quota failed.
                                 */
                                while (i > 0) {
                                        --i;
                                        dq = ip->i_dquot[i];
                                        if (dq == NODQUOT)
                                                continue;
                                        DQI_LOCK(dq);
                                        DQI_WAIT(dq, PINOD, "chkdq3");
                                        ncurblocks = dq->dq_curblocks - change;
                                        if (ncurblocks >= 0)
                                                dq->dq_curblocks = ncurblocks;
                                        else
                                                dq->dq_curblocks = 0;
                                        dq->dq_flags &= ~DQ_BLKS;
                                        dq->dq_flags |= DQ_MOD;
                                        DQI_UNLOCK(dq);
                                }
                                return (error);
                        }
                }
                /* Reset timer when crossing soft limit */
                if (dq->dq_curblocks + change >= dq->dq_bsoftlimit &&
                    dq->dq_curblocks < dq->dq_bsoftlimit)
                        dq->dq_btime = time_second + ITOUMP(ip)->um_btime[i];
                dq->dq_curblocks += change;
                dq->dq_flags |= DQ_MOD;
                DQI_UNLOCK(dq);
                if (warn)
                        uprintf("\n%s: warning, %s disk quota exceeded\n",
                            ITOVFS(ip)->mnt_stat.f_mntonname,
                            quotatypes[i]);
        }
        return (0);
}

/*
 * Check for a valid change to a users allocation.
 * Issue an error message if appropriate.
 */
static int
chkdqchg(struct inode *ip, ufs2_daddr_t change, struct ucred *cred,
    int type, int *warn)
{
        struct dquot *dq = ip->i_dquot[type];
        ufs2_daddr_t ncurblocks = dq->dq_curblocks + change;

        /*
         * If user would exceed their hard limit, disallow space allocation.
         */
        if (ncurblocks >= dq->dq_bhardlimit && dq->dq_bhardlimit) {
                if ((dq->dq_flags & DQ_BLKS) == 0 &&
                    ip->i_uid == cred->cr_uid) {
                        dq->dq_flags |= DQ_BLKS;
                        DQI_UNLOCK(dq);
                        uprintf("\n%s: write failed, %s disk limit reached\n",
                            ITOVFS(ip)->mnt_stat.f_mntonname,
                            quotatypes[type]);
                        return (EDQUOT);
                }
                DQI_UNLOCK(dq);
                return (EDQUOT);
        }
        /*
         * If user is over their soft limit for too long, disallow space
         * allocation. Reset time limit as they cross their soft limit.
         */
        if (ncurblocks >= dq->dq_bsoftlimit && dq->dq_bsoftlimit) {
                if (dq->dq_curblocks < dq->dq_bsoftlimit) {
                        dq->dq_btime = time_second + ITOUMP(ip)->um_btime[type];
                        if (ip->i_uid == cred->cr_uid)
                                *warn = 1;
                        return (0);
                }
                if (time_second > dq->dq_btime) {
                        if ((dq->dq_flags & DQ_BLKS) == 0 &&
                            ip->i_uid == cred->cr_uid) {
                                dq->dq_flags |= DQ_BLKS;
                                DQI_UNLOCK(dq);
                                uprintf("\n%s: write failed, %s "
                                    "disk quota exceeded for too long\n",
                                    ITOVFS(ip)->mnt_stat.f_mntonname,
                                    quotatypes[type]);
                                return (EDQUOT);
                        }
                        DQI_UNLOCK(dq);
                        return (EDQUOT);
                }
        }
        return (0);
}

/*
 * Check the inode limit, applying corrective action.
 */
int
chkiq(struct inode *ip, int change, struct ucred *cred, int flags)
{
        struct dquot *dq;
        int i, error, warn, do_check;

        MPASS(cred != NOCRED || (flags & FORCE) != 0);
#ifdef DIAGNOSTIC
        if ((flags & CHOWN) == 0)
                chkdquot(ip);
#endif
        if (change == 0)
                return (0);
        if (change < 0) {
                for (i = 0; i < MAXQUOTAS; i++) {
                        if ((dq = ip->i_dquot[i]) == NODQUOT)
                                continue;
                        DQI_LOCK(dq);
                        DQI_WAIT(dq, PINOD, "chkiq1");
                        if (dq->dq_curinodes >= -change)
                                dq->dq_curinodes += change;
                        else
                                dq->dq_curinodes = 0;
                        dq->dq_flags &= ~DQ_INODS;
                        dq->dq_flags |= DQ_MOD;
                        DQI_UNLOCK(dq);
                }
                return (0);
        }
        if ((flags & FORCE) == 0 &&
            priv_check_cred(cred, PRIV_VFS_EXCEEDQUOTA))
                do_check = 1;
        else
                do_check = 0;
        for (i = 0; i < MAXQUOTAS; i++) {
                if ((dq = ip->i_dquot[i]) == NODQUOT)
                        continue;
                warn = 0;
                DQI_LOCK(dq);
                DQI_WAIT(dq, PINOD, "chkiq2");
                if (do_check) {
                        error = chkiqchg(ip, change, cred, i, &warn);
                        if (error) {
                                /*
                                 * Roll back user quota changes when
                                 * group quota failed.
                                 */
                                while (i > 0) {
                                        --i;
                                        dq = ip->i_dquot[i];
                                        if (dq == NODQUOT)
                                                continue;
                                        DQI_LOCK(dq);
                                        DQI_WAIT(dq, PINOD, "chkiq3");
                                        if (dq->dq_curinodes >= change)
                                                dq->dq_curinodes -= change;
                                        else
                                                dq->dq_curinodes = 0;
                                        dq->dq_flags &= ~DQ_INODS;
                                        dq->dq_flags |= DQ_MOD;
                                        DQI_UNLOCK(dq);
                                }
                                return (error);
                        }
                }
                /* Reset timer when crossing soft limit */
                if (dq->dq_curinodes + change >= dq->dq_isoftlimit &&
                    dq->dq_curinodes < dq->dq_isoftlimit)
                        dq->dq_itime = time_second + ITOUMP(ip)->um_itime[i];
                dq->dq_curinodes += change;
                dq->dq_flags |= DQ_MOD;
                DQI_UNLOCK(dq);
                if (warn)
                        uprintf("\n%s: warning, %s inode quota exceeded\n",
                            ITOVFS(ip)->mnt_stat.f_mntonname,
                            quotatypes[i]);
        }
        return (0);
}

/*
 * Check for a valid change to a users allocation.
 * Issue an error message if appropriate.
 */
static int
chkiqchg(struct inode *ip, int change, struct ucred *cred, int type, int *warn)
{
        struct dquot *dq = ip->i_dquot[type];
        ino_t ncurinodes = dq->dq_curinodes + change;

        /*
         * If user would exceed their hard limit, disallow inode allocation.
         */
        if (ncurinodes >= dq->dq_ihardlimit && dq->dq_ihardlimit) {
                if ((dq->dq_flags & DQ_INODS) == 0 &&
                    ip->i_uid == cred->cr_uid) {
                        dq->dq_flags |= DQ_INODS;
                        DQI_UNLOCK(dq);
                        uprintf("\n%s: write failed, %s inode limit reached\n",
                            ITOVFS(ip)->mnt_stat.f_mntonname,
                            quotatypes[type]);
                        return (EDQUOT);
                }
                DQI_UNLOCK(dq);
                return (EDQUOT);
        }
        /*
         * If user is over their soft limit for too long, disallow inode
         * allocation. Reset time limit as they cross their soft limit.
         */
        if (ncurinodes >= dq->dq_isoftlimit && dq->dq_isoftlimit) {
                if (dq->dq_curinodes < dq->dq_isoftlimit) {
                        dq->dq_itime = time_second + ITOUMP(ip)->um_itime[type];
                        if (ip->i_uid == cred->cr_uid)
                                *warn = 1;
                        return (0);
                }
                if (time_second > dq->dq_itime) {
                        if ((dq->dq_flags & DQ_INODS) == 0 &&
                            ip->i_uid == cred->cr_uid) {
                                dq->dq_flags |= DQ_INODS;
                                DQI_UNLOCK(dq);
                                uprintf("\n%s: write failed, %s "
                                    "inode quota exceeded for too long\n",
                                    ITOVFS(ip)->mnt_stat.f_mntonname,
                                    quotatypes[type]);
                                return (EDQUOT);
                        }
                        DQI_UNLOCK(dq);
                        return (EDQUOT);
                }
        }
        return (0);
}

#ifdef DIAGNOSTIC
/*
 * On filesystems with quotas enabled, it is an error for a file to change
 * size and not to have a dquot structure associated with it.
 */
static void
chkdquot(struct inode *ip)
{
        struct ufsmount *ump;
        struct vnode *vp;
        int i;

        ump = ITOUMP(ip);
        vp = ITOV(ip);

        /*
         * Disk quotas must be turned off for system files.  Currently
         * these are snapshots and quota files.
         */
        if ((vp->v_vflag & VV_SYSTEM) != 0)
                return;
        /*
         * XXX: Turn off quotas for files with a negative UID or GID.
         * This prevents the creation of 100GB+ quota files.
         */
        if ((int)ip->i_uid < 0 || (int)ip->i_gid < 0)
                return;

        UFS_LOCK(ump);
        for (i = 0; i < MAXQUOTAS; i++) {
                if (ump->um_quotas[i] == NULL ||
                    (ump->um_qflags[i] & (QTF_OPENING|QTF_CLOSING)))
                        continue;
                if (ip->i_dquot[i] == NODQUOT) {
                        UFS_UNLOCK(ump);
                        vn_printf(ITOV(ip), "chkdquot: missing dquot ");
                        panic("chkdquot: missing dquot");
                }
        }
        UFS_UNLOCK(ump);
}
#endif

/*
 * Code to process quotactl commands.
 */

/*
 * Q_QUOTAON - set up a quota file for a particular filesystem.
 */
int
quotaon(struct thread *td, struct mount *mp, int type, void *fname,
    bool *mp_busy)
{
        struct ufsmount *ump;
        struct vnode *vp, **vpp;
        struct vnode *mvp;
        struct dquot *dq;
        int error, flags;
        struct nameidata nd;

        error = priv_check(td, PRIV_UFS_QUOTAON);
        if (error != 0)
                return (error);

        if ((mp->mnt_flag & MNT_RDONLY) != 0)
                return (EROFS);

        ump = VFSTOUFS(mp);
        dq = NODQUOT;

        NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, fname);
        flags = FREAD | FWRITE;
        vfs_ref(mp);
        KASSERT(*mp_busy, ("%s called without busied mount", __func__));
        vfs_unbusy(mp);
        *mp_busy = false;
        error = vn_open(&nd, &flags, 0, NULL);
        if (error != 0) {
                vfs_rel(mp);
                return (error);
        }
        NDFREE_PNBUF(&nd);
        vp = nd.ni_vp;
        error = vfs_busy(mp, MBF_NOWAIT);
        vfs_rel(mp);
        if (error == 0) {
                *mp_busy = true;
                if (vp->v_type != VREG)
                        error = EACCES;
        }
        if (error != 0) {
                VOP_UNLOCK(vp);
                (void) vn_close(vp, FREAD|FWRITE, td->td_ucred, td);
                return (error);
        }

        UFS_LOCK(ump);
        if ((ump->um_qflags[type] & (QTF_OPENING|QTF_CLOSING)) != 0) {
                UFS_UNLOCK(ump);
                VOP_UNLOCK(vp);
                (void) vn_close(vp, FREAD|FWRITE, td->td_ucred, td);
                return (EALREADY);
        }
        ump->um_qflags[type] |= QTF_OPENING|QTF_CLOSING;
        UFS_UNLOCK(ump);
        if ((error = dqopen(vp, ump, type)) != 0) {
                VOP_UNLOCK(vp);
                UFS_LOCK(ump);
                ump->um_qflags[type] &= ~(QTF_OPENING|QTF_CLOSING);
                UFS_UNLOCK(ump);
                (void) vn_close(vp, FREAD|FWRITE, td->td_ucred, td);
                return (error);
        }
        VOP_UNLOCK(vp);
        MNT_ILOCK(mp);
        mp->mnt_flag |= MNT_QUOTA;
        mp->mnt_stat.f_flags |= MNT_QUOTA;
        MNT_IUNLOCK(mp);

        vpp = &ump->um_quotas[type];
        if (*vpp != vp)
                quotaoff1(td, mp, type);

        /*
         * When the directory vnode containing the quota file is
         * inactivated, due to the shared lookup of the quota file
         * vput()ing the dvp, the qsyncvp() call for the containing
         * directory would try to acquire the quota lock exclusive.
         * At the same time, lookup already locked the quota vnode
         * shared.  Mark the quota vnode lock as allowing recursion
         * and automatically converting shared locks to exclusive.
         *
         * Also mark quota vnode as system.
         */
        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        vp->v_vflag |= VV_SYSTEM;
        VN_LOCK_AREC(vp);
        VN_LOCK_DSHARE(vp);
        VOP_UNLOCK(vp);
        *vpp = vp;

        /*
         * Allow the getdq from getinoquota below to read the quota
         * from file.
         */
        UFS_LOCK(ump);
        ump->um_qflags[type] &= ~QTF_CLOSING;
        UFS_UNLOCK(ump);

        /*
         * Save the credential of the process that turned on quotas.
         * Set up the time limits for this quota.
         */
        ump->um_cred[type] = crhold(td->td_ucred);
        ump->um_btime[type] = MAX_DQ_TIME;
        ump->um_itime[type] = MAX_IQ_TIME;
        if (dqget(NULL, 0, ump, type, &dq) == 0) {
                if (dq->dq_btime > 0)
                        ump->um_btime[type] = dq->dq_btime;
                if (dq->dq_itime > 0)
                        ump->um_itime[type] = dq->dq_itime;
                dqrele(NULL, dq);
        }
        /*
         * Search vnodes associated with this mount point,
         * adding references to quota file being opened.
         * NB: only need to add dquot's for inodes being modified.
         */
again:
        MNT_VNODE_FOREACH_ALL(vp, mp, mvp) {
                if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK)) {
                        MNT_VNODE_FOREACH_ALL_ABORT(mp, mvp);
                        goto again;
                }
                if (vp->v_type == VNON || vp->v_writecount <= 0) {
                        vput(vp);
                        continue;
                }
                error = getinoquota(VTOI(vp));
                vput(vp);
                if (error) {
                        MNT_VNODE_FOREACH_ALL_ABORT(mp, mvp);
                        break;
                }
        }

        if (error)
                quotaoff_inchange(td, mp, type);
        UFS_LOCK(ump);
        ump->um_qflags[type] &= ~QTF_OPENING;
        KASSERT((ump->um_qflags[type] & QTF_CLOSING) == 0,
                ("quotaon: leaking flags"));
        UFS_UNLOCK(ump);

        return (error);
}

/*
 * Main code to turn off disk quotas for a filesystem. Does not change
 * flags.
 */
static int
quotaoff1(struct thread *td, struct mount *mp, int type)
{
        struct vnode *vp;
        struct vnode *qvp, *mvp;
        struct ufsmount *ump;
        struct dquot *dq;
        struct inode *ip;
        struct ucred *cr;
        int error;

        ump = VFSTOUFS(mp);

        UFS_LOCK(ump);
        KASSERT((ump->um_qflags[type] & QTF_CLOSING) != 0,
                ("quotaoff1: flags are invalid"));
        if ((qvp = ump->um_quotas[type]) == NULL) {
                UFS_UNLOCK(ump);
                return (0);
        }
        cr = ump->um_cred[type];
        UFS_UNLOCK(ump);

        /*
         * Search vnodes associated with this mount point,
         * deleting any references to quota file being closed.
         */
again:
        MNT_VNODE_FOREACH_ALL(vp, mp, mvp) {
                if (vp->v_type == VNON) {
                        VI_UNLOCK(vp);
                        continue;
                }
                if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK)) {
                        MNT_VNODE_FOREACH_ALL_ABORT(mp, mvp);
                        goto again;
                }
                ip = VTOI(vp);
                dq = ip->i_dquot[type];
                ip->i_dquot[type] = NODQUOT;
                dqrele(vp, dq);
                vput(vp);
        }

        error = dqflush(qvp);
        if (error != 0)
                return (error);

        /*
         * Clear um_quotas before closing the quota vnode to prevent
         * access to the closed vnode from dqget/dqsync
         */
        UFS_LOCK(ump);
        ump->um_quotas[type] = NULL;
        ump->um_cred[type] = NOCRED;
        UFS_UNLOCK(ump);

        vn_lock(qvp, LK_EXCLUSIVE | LK_RETRY);
        qvp->v_vflag &= ~VV_SYSTEM;
        VOP_UNLOCK(qvp);
        error = vn_close(qvp, FREAD|FWRITE, td->td_ucred, td);
        crfree(cr);

        return (error);
}

static int
quotaoff_inchange1(struct thread *td, struct mount *mp, int type)
{
        int error;
        bool need_resume;

        /*
         * mp is already suspended on unmount.  If not, suspend it, to
         * avoid the situation where quotaoff operation eventually
         * failing due to SU structures still keeping references on
         * dquots, but vnode's references are already clean.  This
         * would cause quota accounting leak and asserts otherwise.
         * Note that the thread has already called vn_start_write().
         */
        if (mp->mnt_susp_owner == td) {
                need_resume = false;
        } else {
                error = vfs_write_suspend_umnt(mp);
                if (error != 0)
                        return (error);
                need_resume = true;
        }
        error = quotaoff1(td, mp, type);
        if (need_resume)
                vfs_write_resume(mp, VR_START_WRITE);
        return (error);
}

/*
 * Turns off quotas, assumes that ump->um_qflags are already checked
 * and QTF_CLOSING is set to indicate operation in progress. Fixes
 * ump->um_qflags and mp->mnt_flag after.
 */
int
quotaoff_inchange(struct thread *td, struct mount *mp, int type)
{
        struct ufsmount *ump;
        int error, i;

        error = quotaoff_inchange1(td, mp, type);

        ump = VFSTOUFS(mp);
        UFS_LOCK(ump);
        ump->um_qflags[type] &= ~QTF_CLOSING;
        for (i = 0; i < MAXQUOTAS; i++)
                if (ump->um_quotas[i] != NULL)
                        break;
        if (i == MAXQUOTAS) {
                MNT_ILOCK(mp);
                mp->mnt_flag &= ~MNT_QUOTA;
                mp->mnt_stat.f_flags &= ~MNT_QUOTA;
                MNT_IUNLOCK(mp);
        }
        UFS_UNLOCK(ump);
        return (error);
}

/*
 * Q_QUOTAOFF - turn off disk quotas for a filesystem.
 */
int
quotaoff(struct thread *td, struct mount *mp, int type)
{
        struct ufsmount *ump;
        int error;

        error = priv_check(td, PRIV_UFS_QUOTAOFF);
        if (error)
                return (error);

        ump = VFSTOUFS(mp);
        UFS_LOCK(ump);
        if ((ump->um_qflags[type] & (QTF_OPENING|QTF_CLOSING)) != 0) {
                UFS_UNLOCK(ump);
                return (EALREADY);
        }
        ump->um_qflags[type] |= QTF_CLOSING;
        UFS_UNLOCK(ump);

        return (quotaoff_inchange(td, mp, type));
}

/*
 * Q_GETQUOTA - return current values in a dqblk structure.
 */
static int
_getquota(struct thread *td, struct mount *mp, uint64_t id, int type,
    struct dqblk64 *dqb)
{
        struct dquot *dq;
        int error;

        switch (type) {
        case USRQUOTA:
                if ((td->td_ucred->cr_uid != id) && !unprivileged_get_quota) {
                        error = priv_check(td, PRIV_VFS_GETQUOTA);
                        if (error)
                                return (error);
                }
                break;

        case GRPQUOTA:
                if (!groupmember(id, td->td_ucred) &&
                    !unprivileged_get_quota) {
                        error = priv_check(td, PRIV_VFS_GETQUOTA);
                        if (error)
                                return (error);
                }
                break;

        default:
                return (EINVAL);
        }

        dq = NODQUOT;
        error = dqget(NULL, id, VFSTOUFS(mp), type, &dq);
        if (error)
                return (error);
        *dqb = dq->dq_dqb;
        dqrele(NULL, dq);
        return (error);
}

/*
 * Q_SETQUOTA - assign an entire dqblk structure.
 */
static int
_setquota(struct thread *td, struct mount *mp, uint64_t id, int type,
    struct dqblk64 *dqb)
{
        struct dquot *dq;
        struct dquot *ndq;
        struct ufsmount *ump;
        struct dqblk64 newlim;
        int error;

        error = priv_check(td, PRIV_VFS_SETQUOTA);
        if (error)
                return (error);

        newlim = *dqb;

        ndq = NODQUOT;
        ump = VFSTOUFS(mp);

        error = dqget(NULL, id, ump, type, &ndq);
        if (error)
                return (error);
        dq = ndq;
        DQI_LOCK(dq);
        DQI_WAIT(dq, PINOD, "setqta");
        /*
         * Copy all but the current values.
         * Reset time limit if previously had no soft limit or were
         * under it, but now have a soft limit and are over it.
         */
        newlim.dqb_curblocks = dq->dq_curblocks;
        newlim.dqb_curinodes = dq->dq_curinodes;
        if (dq->dq_id != 0) {
                newlim.dqb_btime = dq->dq_btime;
                newlim.dqb_itime = dq->dq_itime;
        }
        if (newlim.dqb_bsoftlimit &&
            dq->dq_curblocks >= newlim.dqb_bsoftlimit &&
            (dq->dq_bsoftlimit == 0 || dq->dq_curblocks < dq->dq_bsoftlimit))
                newlim.dqb_btime = time_second + ump->um_btime[type];
        if (newlim.dqb_isoftlimit &&
            dq->dq_curinodes >= newlim.dqb_isoftlimit &&
            (dq->dq_isoftlimit == 0 || dq->dq_curinodes < dq->dq_isoftlimit))
                newlim.dqb_itime = time_second + ump->um_itime[type];
        dq->dq_dqb = newlim;
        if (dq->dq_curblocks < dq->dq_bsoftlimit)
                dq->dq_flags &= ~DQ_BLKS;
        if (dq->dq_curinodes < dq->dq_isoftlimit)
                dq->dq_flags &= ~DQ_INODS;
        if (dq->dq_isoftlimit == 0 && dq->dq_bsoftlimit == 0 &&
            dq->dq_ihardlimit == 0 && dq->dq_bhardlimit == 0)
                dq->dq_flags |= DQ_FAKE;
        else
                dq->dq_flags &= ~DQ_FAKE;
        dq->dq_flags |= DQ_MOD;
        DQI_UNLOCK(dq);
        dqrele(NULL, dq);
        return (0);
}

/*
 * Q_SETUSE - set current inode and block usage.
 */
static int
_setuse(struct thread *td, struct mount *mp, uint64_t id, int type,
    struct dqblk64 *dqb)
{
        struct dquot *dq;
        struct ufsmount *ump;
        struct dquot *ndq;
        struct dqblk64 usage;
        int error;

        error = priv_check(td, PRIV_UFS_SETUSE);
        if (error)
                return (error);

        usage = *dqb;

        ump = VFSTOUFS(mp);
        ndq = NODQUOT;

        error = dqget(NULL, id, ump, type, &ndq);
        if (error)
                return (error);
        dq = ndq;
        DQI_LOCK(dq);
        DQI_WAIT(dq, PINOD, "setuse");
        /*
         * Reset time limit if have a soft limit and were
         * previously under it, but are now over it.
         */
        if (dq->dq_bsoftlimit && dq->dq_curblocks < dq->dq_bsoftlimit &&
            usage.dqb_curblocks >= dq->dq_bsoftlimit)
                dq->dq_btime = time_second + ump->um_btime[type];
        if (dq->dq_isoftlimit && dq->dq_curinodes < dq->dq_isoftlimit &&
            usage.dqb_curinodes >= dq->dq_isoftlimit)
                dq->dq_itime = time_second + ump->um_itime[type];
        dq->dq_curblocks = usage.dqb_curblocks;
        dq->dq_curinodes = usage.dqb_curinodes;
        if (dq->dq_curblocks < dq->dq_bsoftlimit)
                dq->dq_flags &= ~DQ_BLKS;
        if (dq->dq_curinodes < dq->dq_isoftlimit)
                dq->dq_flags &= ~DQ_INODS;
        dq->dq_flags |= DQ_MOD;
        DQI_UNLOCK(dq);
        dqrele(NULL, dq);
        return (0);
}

int
getquota32(struct thread *td, struct mount *mp, uint64_t id, int type,
    void *addr)
{
        struct dqblk32 dqb32;
        struct dqblk64 dqb64;
        int error;

        error = _getquota(td, mp, id, type, &dqb64);
        if (error)
                return (error);
        dqb64_dqb32(&dqb64, &dqb32);
        error = copyout(&dqb32, addr, sizeof(dqb32));
        return (error);
}

int
setquota32(struct thread *td, struct mount *mp, uint64_t id, int type,
    void *addr)
{
        struct dqblk32 dqb32;
        struct dqblk64 dqb64;
        int error;

        error = copyin(addr, &dqb32, sizeof(dqb32));
        if (error)
                return (error);
        dqb32_dqb64(&dqb32, &dqb64);
        error = _setquota(td, mp, id, type, &dqb64);
        return (error);
}

int
setuse32(struct thread *td, struct mount *mp, uint64_t id, int type, void *addr)
{
        struct dqblk32 dqb32;
        struct dqblk64 dqb64;
        int error;

        error = copyin(addr, &dqb32, sizeof(dqb32));
        if (error)
                return (error);
        dqb32_dqb64(&dqb32, &dqb64);
        error = _setuse(td, mp, id, type, &dqb64);
        return (error);
}

int
getquota(struct thread *td, struct mount *mp, uint64_t id, int type, void *addr)
{
        struct dqblk64 dqb64;
        int error;

        error = _getquota(td, mp, id, type, &dqb64);
        if (error)
                return (error);
        error = copyout(&dqb64, addr, sizeof(dqb64));
        return (error);
}

int
setquota(struct thread *td, struct mount *mp, uint64_t id, int type, void *addr)
{
        struct dqblk64 dqb64;
        int error;

        error = copyin(addr, &dqb64, sizeof(dqb64));
        if (error)
                return (error);
        error = _setquota(td, mp, id, type, &dqb64);
        return (error);
}

int
setuse(struct thread *td, struct mount *mp, uint64_t id, int type, void *addr)
{
        struct dqblk64 dqb64;
        int error;

        error = copyin(addr, &dqb64, sizeof(dqb64));
        if (error)
                return (error);
        error = _setuse(td, mp, id, type, &dqb64);
        return (error);
}

/*
 * Q_GETQUOTASIZE - get bit-size of quota file fields
 */
int
getquotasize(struct thread *td, struct mount *mp, uint64_t id, int type,
    void *sizep)
{
        struct ufsmount *ump = VFSTOUFS(mp);
        int bitsize;

        UFS_LOCK(ump);
        if (ump->um_quotas[type] == NULL ||
            (ump->um_qflags[type] & QTF_CLOSING)) {
                UFS_UNLOCK(ump);
                return (EINVAL);
        }
        if ((ump->um_qflags[type] & QTF_64BIT) != 0)
                bitsize = 64;
        else
                bitsize = 32;
        UFS_UNLOCK(ump);
        return (copyout(&bitsize, sizep, sizeof(int)));
}

/*
 * Q_SYNC - sync quota files to disk.
 */
int
qsync(struct mount *mp)
{
        struct ufsmount *ump = VFSTOUFS(mp);
        struct vnode *vp, *mvp;
        struct dquot *dq;
        int i, error;

        /*
         * Check if the mount point has any quotas.
         * If not, simply return.
         */
        for (i = 0; i < MAXQUOTAS; i++)
                if (ump->um_quotas[i] != NULL)
                        break;
        if (i == MAXQUOTAS)
                return (0);
        /*
         * Search vnodes associated with this mount point,
         * synchronizing any modified dquot structures.
         */
again:
        MNT_VNODE_FOREACH_ALL(vp, mp, mvp) {
                if (vp->v_type == VNON) {
                        VI_UNLOCK(vp);
                        continue;
                }
                error = vget(vp, LK_EXCLUSIVE | LK_INTERLOCK);
                if (error) {
                        if (error == ENOENT) {
                                MNT_VNODE_FOREACH_ALL_ABORT(mp, mvp);
                                goto again;
                        }
                        continue;
                }
                for (i = 0; i < MAXQUOTAS; i++) {
                        dq = VTOI(vp)->i_dquot[i];
                        if (dq != NODQUOT)
                                dqsync(vp, dq);
                }
                vput(vp);
        }
        return (0);
}

/*
 * Sync quota file for given vnode to disk.
 */
int
qsyncvp(struct vnode *vp)
{
        struct ufsmount *ump = VFSTOUFS(vp->v_mount);
        struct dquot *dq;
        int i;

        /*
         * Check if the mount point has any quotas.
         * If not, simply return.
         */
        for (i = 0; i < MAXQUOTAS; i++)
                if (ump->um_quotas[i] != NULL)
                        break;
        if (i == MAXQUOTAS)
                return (0);
        /*
         * Search quotas associated with this vnode
         * synchronizing any modified dquot structures.
         */
        for (i = 0; i < MAXQUOTAS; i++) {
                dq = VTOI(vp)->i_dquot[i];
                if (dq != NODQUOT)
                        dqsync(vp, dq);
        }
        return (0);
}

/*
 * Code pertaining to management of the in-core dquot data structures.
 */
#define DQHASH(dqvp, id) \
        (&dqhashtbl[((((intptr_t)(dqvp)) >> 8) + id) & dqhash])
static LIST_HEAD(dqhash, dquot) *dqhashtbl;
static u_long dqhash;

/*
 * Dquot free list.
 */
#define DQUOTINC        5       /* minimum free dquots desired */
static TAILQ_HEAD(dqfreelist, dquot) dqfreelist;
static long numdquot, desireddquot = DQUOTINC;

/*
 * Lock to protect quota hash, dq free list and dq_cnt ref counters of
 * _all_ dqs.
 */
struct mtx dqhlock;

#define DQH_LOCK()      mtx_lock(&dqhlock)
#define DQH_UNLOCK()    mtx_unlock(&dqhlock)

static struct dquot *dqhashfind(struct dqhash *dqh, uint64_t id,
        struct vnode *dqvp);

/*
 * Initialize the quota system.
 */
void
dqinit(void)
{

        mtx_init(&dqhlock, "dqhlock", NULL, MTX_DEF);
        dqhashtbl = hashinit(desiredvnodes, M_DQUOT, &dqhash);
        TAILQ_INIT(&dqfreelist);
}

/*
 * Shut down the quota system.
 */
void
dquninit(void)
{
        struct dquot *dq;

        hashdestroy(dqhashtbl, M_DQUOT, dqhash);
        while ((dq = TAILQ_FIRST(&dqfreelist)) != NULL) {
                TAILQ_REMOVE(&dqfreelist, dq, dq_freelist);
                mtx_destroy(&dq->dq_lock);
                free(dq, M_DQUOT);
        }
        mtx_destroy(&dqhlock);
}

static struct dquot *
dqhashfind(struct dqhash *dqh, uint64_t id, struct vnode *dqvp)
{
        struct dquot *dq;

        mtx_assert(&dqhlock, MA_OWNED);
        LIST_FOREACH(dq, dqh, dq_hash) {
                if (dq->dq_id != id ||
                    dq->dq_ump->um_quotas[dq->dq_type] != dqvp)
                        continue;
                /*
                 * Cache hit with no references.  Take
                 * the structure off the free list.
                 */
                if (dq->dq_cnt == 0)
                        TAILQ_REMOVE(&dqfreelist, dq, dq_freelist);
                DQREF(dq);
                return (dq);
        }
        return (NODQUOT);
}

/*
 * Determine the quota file type.
 *
 * A 32-bit quota file is simply an array of struct dqblk32.
 *
 * A 64-bit quota file is a struct dqhdr64 followed by an array of struct
 * dqblk64.  The header contains various magic bits which allow us to be
 * reasonably confident that it is indeeda 64-bit quota file and not just
 * a 32-bit quota file that just happens to "look right".
 *
 */
static int
dqopen(struct vnode *vp, struct ufsmount *ump, int type)
{
        struct dqhdr64 dqh;
        struct iovec aiov;
        struct uio auio;
        int error;

        ASSERT_VOP_LOCKED(vp, "dqopen");
        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        aiov.iov_base = &dqh;
        aiov.iov_len = sizeof(dqh);
        auio.uio_resid = sizeof(dqh);
        auio.uio_offset = 0;
        auio.uio_segflg = UIO_SYSSPACE;
        auio.uio_rw = UIO_READ;
        auio.uio_td = (struct thread *)0;
        error = VOP_READ(vp, &auio, 0, ump->um_cred[type]);

        if (error != 0)
                return (error);
        if (auio.uio_resid > 0) {
                /* assume 32 bits */
                return (0);
        }

        UFS_LOCK(ump);
        if (strcmp(dqh.dqh_magic, Q_DQHDR64_MAGIC) == 0 &&
            be32toh(dqh.dqh_version) == Q_DQHDR64_VERSION &&
            be32toh(dqh.dqh_hdrlen) == (uint32_t)sizeof(struct dqhdr64) &&
            be32toh(dqh.dqh_reclen) == (uint32_t)sizeof(struct dqblk64)) {
                /* XXX: what if the magic matches, but the sizes are wrong? */
                ump->um_qflags[type] |= QTF_64BIT;
        } else {
                ump->um_qflags[type] &= ~QTF_64BIT;
        }
        UFS_UNLOCK(ump);

        return (0);
}

/*
 * Obtain a dquot structure for the specified identifier and quota file
 * reading the information from the file if necessary.
 */
static int
dqget(struct vnode *vp, uint64_t id, struct ufsmount *ump, int type,
    struct dquot **dqp)
{
        uint8_t buf[sizeof(struct dqblk64)];
        off_t base, recsize;
        struct dquot *dq, *dq1;
        struct dqhash *dqh;
        struct vnode *dqvp;
        struct iovec aiov;
        struct uio auio;
        int dqvplocked, error;

        if (vp != NULL)
                ASSERT_VOP_ELOCKED(vp, "dqget");

        if (vp != NULL && *dqp != NODQUOT) {
                return (0);
        }

        /* XXX: Disallow negative id values to prevent the
        * creation of 100GB+ quota data files.
        */
        if ((int)id < 0)
                return (EINVAL);

        UFS_LOCK(ump);
        dqvp = ump->um_quotas[type];
        if (dqvp == NULL || (ump->um_qflags[type] & QTF_CLOSING)) {
                *dqp = NODQUOT;
                UFS_UNLOCK(ump);
                return (EINVAL);
        }
        vref(dqvp);
        UFS_UNLOCK(ump);
        error = 0;
        dqvplocked = 0;

        /*
         * Check the cache first.
         */
        dqh = DQHASH(dqvp, id);
        DQH_LOCK();
        dq = dqhashfind(dqh, id, dqvp);
        if (dq != NULL) {
                DQH_UNLOCK();
hfound:         DQI_LOCK(dq);
                DQI_WAIT(dq, PINOD, "dqget");
                DQI_UNLOCK(dq);
                if (dq->dq_ump == NULL) {
                        dqrele(vp, dq);
                        dq = NODQUOT;
                        error = EIO;
                }
                *dqp = dq;
                if (dqvplocked)
                        vput(dqvp);
                else
                        vrele(dqvp);
                return (error);
        }

        /*
         * Quota vnode lock is before DQ_LOCK. Acquire dqvp lock there
         * since new dq will appear on the hash chain DQ_LOCKed.
         */
        if (vp != dqvp) {
                DQH_UNLOCK();
                vn_lock(dqvp, LK_SHARED | LK_RETRY);
                dqvplocked = 1;
                DQH_LOCK();
                /*
                 * Recheck the cache after sleep for quota vnode lock.
                 */
                dq = dqhashfind(dqh, id, dqvp);
                if (dq != NULL) {
                        DQH_UNLOCK();
                        goto hfound;
                }
        }

        /*
         * Not in cache, allocate a new one or take it from the
         * free list.
         */
        if (TAILQ_FIRST(&dqfreelist) == NODQUOT &&
            numdquot < MAXQUOTAS * desiredvnodes)
                desireddquot += DQUOTINC;
        if (numdquot < desireddquot) {
                numdquot++;
                DQH_UNLOCK();
                dq1 = malloc(sizeof *dq1, M_DQUOT, M_WAITOK | M_ZERO);
                mtx_init(&dq1->dq_lock, "dqlock", NULL, MTX_DEF);
                DQH_LOCK();
                /*
                 * Recheck the cache after sleep for memory.
                 */
                dq = dqhashfind(dqh, id, dqvp);
                if (dq != NULL) {
                        numdquot--;
                        DQH_UNLOCK();
                        mtx_destroy(&dq1->dq_lock);
                        free(dq1, M_DQUOT);
                        goto hfound;
                }
                dq = dq1;
        } else {
                if ((dq = TAILQ_FIRST(&dqfreelist)) == NULL) {
                        DQH_UNLOCK();
                        tablefull("dquot");
                        *dqp = NODQUOT;
                        if (dqvplocked)
                                vput(dqvp);
                        else
                                vrele(dqvp);
                        return (EUSERS);
                }
                if (dq->dq_cnt || (dq->dq_flags & DQ_MOD))
                        panic("dqget: free dquot isn't %p", dq);
                TAILQ_REMOVE(&dqfreelist, dq, dq_freelist);
                if (dq->dq_ump != NULL)
                        LIST_REMOVE(dq, dq_hash);
        }

        /*
         * Dq is put into hash already locked to prevent parallel
         * usage while it is being read from file.
         */
        dq->dq_flags = DQ_LOCK;
        dq->dq_id = id;
        dq->dq_type = type;
        dq->dq_ump = ump;
        LIST_INSERT_HEAD(dqh, dq, dq_hash);
        DQREF(dq);
        DQH_UNLOCK();

        /*
         * Read the requested quota record from the quota file, performing
         * any necessary conversions.
         */
        if (ump->um_qflags[type] & QTF_64BIT) {
                recsize = sizeof(struct dqblk64);
                base = sizeof(struct dqhdr64);
        } else {
                recsize = sizeof(struct dqblk32);
                base = 0;
        }
        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        aiov.iov_base = buf;
        aiov.iov_len = recsize;
        auio.uio_resid = recsize;
        auio.uio_offset = base + id * recsize;
        auio.uio_segflg = UIO_SYSSPACE;
        auio.uio_rw = UIO_READ;
        auio.uio_td = (struct thread *)0;

        error = VOP_READ(dqvp, &auio, 0, ump->um_cred[type]);
        if (auio.uio_resid == recsize && error == 0) {
                bzero(&dq->dq_dqb, sizeof(dq->dq_dqb));
        } else {
                if (ump->um_qflags[type] & QTF_64BIT)
                        dqb64_dq((struct dqblk64 *)buf, dq);
                else
                        dqb32_dq((struct dqblk32 *)buf, dq);
        }
        if (dqvplocked)
                vput(dqvp);
        else
                vrele(dqvp);
        /*
         * I/O error in reading quota file, release
         * quota structure and reflect problem to caller.
         */
        if (error) {
                DQH_LOCK();
                dq->dq_ump = NULL;
                LIST_REMOVE(dq, dq_hash);
                DQH_UNLOCK();
                DQI_LOCK(dq);
                if (dq->dq_flags & DQ_WANT)
                        wakeup(dq);
                dq->dq_flags = 0;
                DQI_UNLOCK(dq);
                dqrele(vp, dq);
                *dqp = NODQUOT;
                return (error);
        }
        DQI_LOCK(dq);
        /*
         * Check for no limit to enforce.
         * Initialize time values if necessary.
         */
        if (dq->dq_isoftlimit == 0 && dq->dq_bsoftlimit == 0 &&
            dq->dq_ihardlimit == 0 && dq->dq_bhardlimit == 0)
                dq->dq_flags |= DQ_FAKE;
        if (dq->dq_id != 0) {
                if (dq->dq_btime == 0) {
                        dq->dq_btime = time_second + ump->um_btime[type];
                        if (dq->dq_bsoftlimit &&
                            dq->dq_curblocks >= dq->dq_bsoftlimit)
                                dq->dq_flags |= DQ_MOD;
                }
                if (dq->dq_itime == 0) {
                        dq->dq_itime = time_second + ump->um_itime[type];
                        if (dq->dq_isoftlimit &&
                            dq->dq_curinodes >= dq->dq_isoftlimit)
                                dq->dq_flags |= DQ_MOD;
                }
        }
        DQI_WAKEUP(dq);
        DQI_UNLOCK(dq);
        *dqp = dq;
        return (0);
}

#ifdef DIAGNOSTIC
/*
 * Obtain a reference to a dquot.
 */
static void
dqref(struct dquot *dq)
{

        dq->dq_cnt++;
}
#endif

/*
 * Release a reference to a dquot.
 */
void
dqrele(struct vnode *vp, struct dquot *dq)
{

        if (dq == NODQUOT)
                return;
        DQH_LOCK();
        KASSERT(dq->dq_cnt > 0, ("Lost dq %p reference 1", dq));
        if (dq->dq_cnt > 1) {
                dq->dq_cnt--;
                DQH_UNLOCK();
                return;
        }
        DQH_UNLOCK();
sync:
        (void) dqsync(vp, dq);

        DQH_LOCK();
        KASSERT(dq->dq_cnt > 0, ("Lost dq %p reference 2", dq));
        if (--dq->dq_cnt > 0)
        {
                DQH_UNLOCK();
                return;
        }

        /*
         * The dq may become dirty after it is synced but before it is
         * put to the free list. Checking the DQ_MOD there without
         * locking dq should be safe since no other references to the
         * dq exist.
         */
        if ((dq->dq_flags & DQ_MOD) != 0) {
                dq->dq_cnt++;
                DQH_UNLOCK();
                goto sync;
        }
        TAILQ_INSERT_TAIL(&dqfreelist, dq, dq_freelist);
        DQH_UNLOCK();
}

/*
 * Update the disk quota in the quota file.
 */
static int
dqsync(struct vnode *vp, struct dquot *dq)
{
        uint8_t buf[sizeof(struct dqblk64)];
        off_t base, recsize;
        struct vnode *dqvp;
        struct iovec aiov;
        struct uio auio;
        int error;
        struct mount *mp;
        struct ufsmount *ump;

        if (vp != NULL)
                ASSERT_VOP_ELOCKED(vp, "dqsync");

        mp = NULL;
        error = 0;
        if (dq == NODQUOT)
                panic("dqsync: dquot");
        if ((ump = dq->dq_ump) == NULL)
                return (0);
        UFS_LOCK(ump);
        if ((dqvp = ump->um_quotas[dq->dq_type]) == NULL) {
                if (vp == NULL) {
                        UFS_UNLOCK(ump);
                        return (0);
                } else
                        panic("dqsync: file");
        }
        vref(dqvp);
        UFS_UNLOCK(ump);

        DQI_LOCK(dq);
        if ((dq->dq_flags & DQ_MOD) == 0) {
                DQI_UNLOCK(dq);
                vrele(dqvp);
                return (0);
        }
        DQI_UNLOCK(dq);

        (void) vn_start_secondary_write(dqvp, &mp, V_WAIT);
        if (vp != dqvp)
                vn_lock(dqvp, LK_EXCLUSIVE | LK_RETRY);

        DQI_LOCK(dq);
        DQI_WAIT(dq, PINOD, "dqsync");
        if ((dq->dq_flags & DQ_MOD) == 0)
                goto out;
        dq->dq_flags |= DQ_LOCK;
        DQI_UNLOCK(dq);

        /*
         * Write the quota record to the quota file, performing any
         * necessary conversions.  See dqget() for additional details.
         */
        if (ump->um_qflags[dq->dq_type] & QTF_64BIT) {
                dq_dqb64(dq, (struct dqblk64 *)buf);
                recsize = sizeof(struct dqblk64);
                base = sizeof(struct dqhdr64);
        } else {
                dq_dqb32(dq, (struct dqblk32 *)buf);
                recsize = sizeof(struct dqblk32);
                base = 0;
        }

        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        aiov.iov_base = buf;
        aiov.iov_len = recsize;
        auio.uio_resid = recsize;
        auio.uio_offset = base + dq->dq_id * recsize;
        auio.uio_segflg = UIO_SYSSPACE;
        auio.uio_rw = UIO_WRITE;
        auio.uio_td = (struct thread *)0;
        error = VOP_WRITE(dqvp, &auio, 0, dq->dq_ump->um_cred[dq->dq_type]);
        if (auio.uio_resid && error == 0)
                error = EIO;

        DQI_LOCK(dq);
        DQI_WAKEUP(dq);
        dq->dq_flags &= ~DQ_MOD;
out:
        DQI_UNLOCK(dq);
        if (vp != dqvp)
                vput(dqvp);
        else
                vrele(dqvp);
        vn_finished_secondary_write(mp);
        return (error);
}

/*
 * Flush all entries from the cache for a particular vnode.
 */
static int
dqflush(struct vnode *vp)
{
        struct dquot *dq, *nextdq;
        struct dqhash *dqh;
        int error;

        /*
         * Move all dquot's that used to refer to this quota
         * file off their hash chains (they will eventually
         * fall off the head of the free list and be re-used).
         */
        error = 0;
        DQH_LOCK();
        for (dqh = &dqhashtbl[dqhash]; dqh >= dqhashtbl; dqh--) {
                for (dq = LIST_FIRST(dqh); dq; dq = nextdq) {
                        nextdq = LIST_NEXT(dq, dq_hash);
                        if (dq->dq_ump->um_quotas[dq->dq_type] != vp)
                                continue;
                        if (dq->dq_cnt)
                                error = EBUSY;
                        else {
                                LIST_REMOVE(dq, dq_hash);
                                dq->dq_ump = NULL;
                        }
                }
        }
        DQH_UNLOCK();
        return (error);
}

/*
 * The following three functions are provided for the adjustment of
 * quotas by the soft updates code.
 */
#ifdef SOFTUPDATES
/*
 * Acquire a reference to the quota structures associated with a vnode.
 * Return count of number of quota structures found.
 */
int
quotaref(struct vnode *vp, struct dquot **qrp)
{
        struct inode *ip;
        struct dquot *dq;
        int i, found;

        for (i = 0; i < MAXQUOTAS; i++)
                qrp[i] = NODQUOT;
        /*
         * Disk quotas must be turned off for system files.  Currently
         * snapshot and quota files.
         */
        if ((vp->v_vflag & VV_SYSTEM) != 0)
                return (0);
        /*
         * Iterate through and copy active quotas.
         */
        found = 0;
        ip = VTOI(vp);
        mtx_lock(&dqhlock);
        for (i = 0; i < MAXQUOTAS; i++) {
                if ((dq = ip->i_dquot[i]) == NODQUOT)
                        continue;
                DQREF(dq);
                qrp[i] = dq;
                found++;
        }
        mtx_unlock(&dqhlock);
        return (found);
}

/*
 * Release a set of quota structures obtained from a vnode.
 */
void
quotarele(struct dquot **qrp)
{
        struct dquot *dq;
        int i;

        for (i = 0; i < MAXQUOTAS; i++) {
                if ((dq = qrp[i]) == NODQUOT)
                        continue;
                dqrele(NULL, dq);
        }
}

/*
 * Adjust the number of blocks associated with a quota.
 * Positive numbers when adding blocks; negative numbers when freeing blocks.
 */
void
quotaadj(struct dquot **qrp, struct ufsmount *ump, int64_t blkcount)
{
        struct dquot *dq;
        ufs2_daddr_t ncurblocks;
        int i;

        if (blkcount == 0)
                return;
        for (i = 0; i < MAXQUOTAS; i++) {
                if ((dq = qrp[i]) == NODQUOT)
                        continue;
                DQI_LOCK(dq);
                DQI_WAIT(dq, PINOD, "adjqta");
                ncurblocks = dq->dq_curblocks + blkcount;
                if (ncurblocks >= 0)
                        dq->dq_curblocks = ncurblocks;
                else
                        dq->dq_curblocks = 0;
                if (blkcount < 0)
                        dq->dq_flags &= ~DQ_BLKS;
                else if (dq->dq_curblocks + blkcount >= dq->dq_bsoftlimit &&
                         dq->dq_curblocks < dq->dq_bsoftlimit)
                        dq->dq_btime = time_second + ump->um_btime[i];
                dq->dq_flags |= DQ_MOD;
                DQI_UNLOCK(dq);
        }
}
#endif /* SOFTUPDATES */

/*
 * 32-bit / 64-bit conversion functions.
 *
 * 32-bit quota records are stored in native byte order.  Attention must
 * be paid to overflow issues.
 *
 * 64-bit quota records are stored in network byte order.
 */

#define CLIP32(u64) (u64 > UINT32_MAX ? UINT32_MAX : (uint32_t)u64)

/*
 * Convert 32-bit host-order structure to dquot.
 */
static void
dqb32_dq(const struct dqblk32 *dqb32, struct dquot *dq)
{

        dq->dq_bhardlimit = dqb32->dqb_bhardlimit;
        dq->dq_bsoftlimit = dqb32->dqb_bsoftlimit;
        dq->dq_curblocks = dqb32->dqb_curblocks;
        dq->dq_ihardlimit = dqb32->dqb_ihardlimit;
        dq->dq_isoftlimit = dqb32->dqb_isoftlimit;
        dq->dq_curinodes = dqb32->dqb_curinodes;
        dq->dq_btime = dqb32->dqb_btime;
        dq->dq_itime = dqb32->dqb_itime;
}

/*
 * Convert 64-bit network-order structure to dquot.
 */
static void
dqb64_dq(const struct dqblk64 *dqb64, struct dquot *dq)
{

        dq->dq_bhardlimit = be64toh(dqb64->dqb_bhardlimit);
        dq->dq_bsoftlimit = be64toh(dqb64->dqb_bsoftlimit);
        dq->dq_curblocks = be64toh(dqb64->dqb_curblocks);
        dq->dq_ihardlimit = be64toh(dqb64->dqb_ihardlimit);
        dq->dq_isoftlimit = be64toh(dqb64->dqb_isoftlimit);
        dq->dq_curinodes = be64toh(dqb64->dqb_curinodes);
        dq->dq_btime = be64toh(dqb64->dqb_btime);
        dq->dq_itime = be64toh(dqb64->dqb_itime);
}

/*
 * Convert dquot to 32-bit host-order structure.
 */
static void
dq_dqb32(const struct dquot *dq, struct dqblk32 *dqb32)
{

        dqb32->dqb_bhardlimit = CLIP32(dq->dq_bhardlimit);
        dqb32->dqb_bsoftlimit = CLIP32(dq->dq_bsoftlimit);
        dqb32->dqb_curblocks = CLIP32(dq->dq_curblocks);
        dqb32->dqb_ihardlimit = CLIP32(dq->dq_ihardlimit);
        dqb32->dqb_isoftlimit = CLIP32(dq->dq_isoftlimit);
        dqb32->dqb_curinodes = CLIP32(dq->dq_curinodes);
        dqb32->dqb_btime = CLIP32(dq->dq_btime);
        dqb32->dqb_itime = CLIP32(dq->dq_itime);
}

/*
 * Convert dquot to 64-bit network-order structure.
 */
static void
dq_dqb64(const struct dquot *dq, struct dqblk64 *dqb64)
{

        dqb64->dqb_bhardlimit = htobe64(dq->dq_bhardlimit);
        dqb64->dqb_bsoftlimit = htobe64(dq->dq_bsoftlimit);
        dqb64->dqb_curblocks = htobe64(dq->dq_curblocks);
        dqb64->dqb_ihardlimit = htobe64(dq->dq_ihardlimit);
        dqb64->dqb_isoftlimit = htobe64(dq->dq_isoftlimit);
        dqb64->dqb_curinodes = htobe64(dq->dq_curinodes);
        dqb64->dqb_btime = htobe64(dq->dq_btime);
        dqb64->dqb_itime = htobe64(dq->dq_itime);
}

/*
 * Convert 64-bit host-order structure to 32-bit host-order structure.
 */
static void
dqb64_dqb32(const struct dqblk64 *dqb64, struct dqblk32 *dqb32)
{

        dqb32->dqb_bhardlimit = CLIP32(dqb64->dqb_bhardlimit);
        dqb32->dqb_bsoftlimit = CLIP32(dqb64->dqb_bsoftlimit);
        dqb32->dqb_curblocks = CLIP32(dqb64->dqb_curblocks);
        dqb32->dqb_ihardlimit = CLIP32(dqb64->dqb_ihardlimit);
        dqb32->dqb_isoftlimit = CLIP32(dqb64->dqb_isoftlimit);
        dqb32->dqb_curinodes = CLIP32(dqb64->dqb_curinodes);
        dqb32->dqb_btime = CLIP32(dqb64->dqb_btime);
        dqb32->dqb_itime = CLIP32(dqb64->dqb_itime);
}

/*
 * Convert 32-bit host-order structure to 64-bit host-order structure.
 */
static void
dqb32_dqb64(const struct dqblk32 *dqb32, struct dqblk64 *dqb64)
{

        dqb64->dqb_bhardlimit = dqb32->dqb_bhardlimit;
        dqb64->dqb_bsoftlimit = dqb32->dqb_bsoftlimit;
        dqb64->dqb_curblocks = dqb32->dqb_curblocks;
        dqb64->dqb_ihardlimit = dqb32->dqb_ihardlimit;
        dqb64->dqb_isoftlimit = dqb32->dqb_isoftlimit;
        dqb64->dqb_curinodes = dqb32->dqb_curinodes;
        dqb64->dqb_btime = dqb32->dqb_btime;
        dqb64->dqb_itime = dqb32->dqb_itime;
}