/*      $OpenBSD: ufs_quota.c,v 1.48 2025/09/20 13:53:36 mpi Exp $      */
/*      $NetBSD: ufs_quota.c,v 1.8 1996/02/09 22:36:09 christos Exp $   */

/*
 * 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.
 *
 *      @(#)ufs_quota.c 8.5 (Berkeley) 8/19/94
 */

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/namei.h>
#include <sys/malloc.h>
#include <sys/fcntl.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/ktrace.h>

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

#include <sys/queue.h>

#include <crypto/siphash.h>

/*
 * The following structure records disk usage for a user or group on a
 * filesystem. There is one allocated for each quota that exists on any
 * filesystem for the current user or group. A cache is kept of recently
 * used entries.
 */
struct dquot {
        LIST_ENTRY(dquot) dq_hash;      /* hash list */
        TAILQ_ENTRY(dquot) dq_freelist; /* free list */
        u_int16_t dq_flags;             /* flags, see below */
        u_int16_t dq_type;              /* quota type of this dquot */
        u_int32_t dq_cnt;               /* count of active references */
        u_int32_t dq_id;                /* identifier this applies to */
        struct  vnode *dq_vp;           /* file backing this quota */
        struct  ucred  *dq_cred;        /* credentials for writing file */
        struct  dqblk dq_dqb;           /* actual usage & quotas */
};

/*
 * Flag values.
 */
#define DQ_LOCK         0x01            /* this quota locked (no MODS) */
#define DQ_WANT         0x02            /* wakeup on unlock */
#define DQ_MOD          0x04            /* this quota modified since read */
#define DQ_FAKE         0x08            /* no limits here, just usage */
#define DQ_BLKS         0x10            /* has been warned about blk limit */
#define DQ_INODS        0x20            /* has been warned about inode limit */

/*
 * Shorthand notation.
 */
#define dq_bhardlimit   dq_dqb.dqb_bhardlimit
#define dq_bsoftlimit   dq_dqb.dqb_bsoftlimit
#define dq_curblocks    dq_dqb.dqb_curblocks
#define dq_ihardlimit   dq_dqb.dqb_ihardlimit
#define dq_isoftlimit   dq_dqb.dqb_isoftlimit
#define dq_curinodes    dq_dqb.dqb_curinodes
#define dq_btime        dq_dqb.dqb_btime
#define dq_itime        dq_dqb.dqb_itime

/*
 * If the system has never checked for a quota for this file, then it is
 * set to NODQUOT.  Once a write attempt is made the inode pointer is set
 * to reference a dquot structure.
 */
#define NODQUOT         NULL

void    dqref(struct dquot *);
void    dqrele(struct vnode *, struct dquot *);
int     dqsync(struct vnode *, struct dquot *);

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

int     getquota(struct mount *, u_long, int, caddr_t);
int     quotaon(struct proc *, struct mount *, int, caddr_t);
int     setquota(struct mount *, u_long, int, caddr_t);
int     setuse(struct mount *, u_long, int, caddr_t);

int     chkdqchg(struct inode *, long, struct ucred *, int);
int     chkiqchg(struct inode *, long, struct ucred *, int);

int dqget(struct vnode *, u_long, struct ufsmount *, int,
               struct dquot **);

int     quotaon_vnode(struct vnode *, void *);
int     quotaoff_vnode(struct vnode *, void *);
int     qsync_vnode(struct vnode *, void *);

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

/*
 * Obtain a reference to a dquot.
 */
void
dqref(struct dquot *dq)
{
        dq->dq_cnt++;
}

/*
 * 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 quotas.h should be increased, and the
 * additional dquots set up here.
 */
int
getinoquota(struct inode *ip)
{
        struct ufsmount *ump;
        struct vnode *vp = ITOV(ip);
        int error;

        ump = ip->i_ump;
        /*
         * Set up the user quota based on file uid.
         * EINVAL means that quotas are not enabled.
         */
        if (ip->i_dquot[USRQUOTA] == NODQUOT &&
            (error =
                dqget(vp, DIP(ip, 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 (ip->i_dquot[GRPQUOTA] == NODQUOT &&
            (error =
                dqget(vp, DIP(ip, gid), ump, GRPQUOTA, &ip->i_dquot[GRPQUOTA])) &&
            error != EINVAL)
                return (error);
        return (0);
}

/*
 * Update disk usage, and take corrective action.
 */
int 
ufs_quota_alloc_blocks2(struct inode *ip, daddr_t change,
    struct ucred *cred, enum ufs_quota_flags flags)
{
        struct dquot *dq;
        int i;
        int error;

#ifdef DIAGNOSTIC
        chkdquot(ip);
#endif

        if (change == 0)
                return (0);

        if ((flags & UFS_QUOTA_FORCE) == 0 && 
            (cred != NOCRED && cred->cr_uid != 0)) {
                for (i = 0; i < MAXQUOTAS; i++) {
                        if (flags & (1 << i)) 
                                continue;
                        if ((dq = ip->i_dquot[i]) == NODQUOT)
                                continue;
                        if ((error = chkdqchg(ip, change, cred, i)) != 0)
                                return (error);
                }
        }
        for (i = 0; i < MAXQUOTAS; i++) {
                if (flags & (1 << i))
                        continue;
                if ((dq = ip->i_dquot[i]) == NODQUOT)
                        continue;
                while (dq->dq_flags & DQ_LOCK) {
                        dq->dq_flags |= DQ_WANT;
                        tsleep_nsec(dq, PINOD+1, "chkdq", INFSLP);
                }
                dq->dq_curblocks += change;
                dq->dq_flags |= DQ_MOD;
        }
        return (0);
}

int
ufs_quota_free_blocks2(struct inode *ip, daddr_t change,
    struct ucred *cred, enum ufs_quota_flags flags)
{
        struct dquot *dq;
        int i;

#ifdef DIAGNOSTIC
        if (!VOP_ISLOCKED(ITOV(ip))) 
                panic ("ufs_quota_free_blocks2: vnode is not locked");
#endif

        if (change == 0) 
                return (0);

        for (i = 0; i < MAXQUOTAS; i++) {
                if (flags & (1 << i))
                        continue;
                if ((dq = ip->i_dquot[i]) == NODQUOT)
                        continue;
                while (dq->dq_flags & DQ_LOCK) {
                        dq->dq_flags |= DQ_WANT;
                        tsleep_nsec(dq, PINOD+1, "chkdq", INFSLP);
                }
                if (dq->dq_curblocks >= change)
                        dq->dq_curblocks -= change;
                else
                        dq->dq_curblocks = 0;
                dq->dq_flags &= ~DQ_BLKS;
                dq->dq_flags |= DQ_MOD;
        }
        return (0);
}

/*
 * Check for a valid change to a users allocation.
 * Issue an error message if appropriate.
 */
int
chkdqchg(struct inode *ip, long change, struct ucred *cred, int type)
{
        struct dquot *dq = ip->i_dquot[type];
        long 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 &&
                    DIP(ip, uid) == cred->cr_uid) {
                        uprintf("\n%s: write failed, %s disk limit reached\n",
                            ITOV(ip)->v_mount->mnt_stat.f_mntonname,
                            quotatypes[type]);
                        dq->dq_flags |= DQ_BLKS;
                }
                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 = gettime() + ip->i_ump->um_btime[type];
                        if (DIP(ip, uid) == cred->cr_uid)
                                uprintf("\n%s: warning, %s %s\n",
                                    ITOV(ip)->v_mount->mnt_stat.f_mntonname,
                                    quotatypes[type], "disk quota exceeded");
                        return (0);
                }
                if (gettime() > dq->dq_btime) {
                        if ((dq->dq_flags & DQ_BLKS) == 0 &&
                            DIP(ip, uid) == cred->cr_uid) {
                                uprintf("\n%s: write failed, %s %s\n",
                                    ITOV(ip)->v_mount->mnt_stat.f_mntonname,
                                    quotatypes[type],
                                    "disk quota exceeded for too long");
                                dq->dq_flags |= DQ_BLKS;
                        }
                        return (EDQUOT);
                }
        }
        return (0);
}

/*
 * Check the inode limit, applying corrective action.
 */
int
ufs_quota_alloc_inode2(struct inode *ip, struct ucred *cred,
    enum ufs_quota_flags flags)
{
        struct dquot *dq;
        int i;
        int error;

#ifdef DIAGNOSTIC
        chkdquot(ip);
#endif

        if ((flags & UFS_QUOTA_FORCE) == 0 && cred->cr_uid != 0) {
                for (i = 0; i < MAXQUOTAS; i++) {
                        if (flags & (1 << i)) 
                                continue;
                        if ((dq = ip->i_dquot[i]) == NODQUOT)
                                continue;
                        if ((error = chkiqchg(ip, 1, cred, i)) != 0)
                                return (error);
                }
        }
        for (i = 0; i < MAXQUOTAS; i++) {
                if (flags & (1 << i)) 
                        continue;
                if ((dq = ip->i_dquot[i]) == NODQUOT)
                        continue;
                while (dq->dq_flags & DQ_LOCK) {
                        dq->dq_flags |= DQ_WANT;
                        tsleep_nsec(dq, PINOD+1, "chkiq", INFSLP);
                }
                dq->dq_curinodes++;
                dq->dq_flags |= DQ_MOD;
        }
        return (0);
}

int
ufs_quota_free_inode2(struct inode *ip, struct ucred *cred,
    enum ufs_quota_flags flags)
{
        struct dquot *dq;
        int i;

#ifdef DIAGNOSTIC
        if (!VOP_ISLOCKED(ITOV(ip))) 
                panic ("ufs_quota_free_blocks2: vnode is not locked");
#endif

        for (i = 0; i < MAXQUOTAS; i++) {
                if (flags & (1 << i)) 
                        continue;
                if ((dq = ip->i_dquot[i]) == NODQUOT)
                        continue;
                while (dq->dq_flags & DQ_LOCK) {
                        dq->dq_flags |= DQ_WANT;
                        tsleep_nsec(dq, PINOD+1, "chkiq", INFSLP);
                }
                if (dq->dq_curinodes > 0)
                        dq->dq_curinodes--;
                dq->dq_flags &= ~DQ_INODS;
                dq->dq_flags |= DQ_MOD;
        }
        return (0);
}

/*
 * Check for a valid change to a users allocation.
 * Issue an error message if appropriate.
 */
int
chkiqchg(struct inode *ip, long change, struct ucred *cred, int type)
{
        struct dquot *dq = ip->i_dquot[type];
        long 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 &&
                    DIP(ip, uid) == cred->cr_uid) {
                        uprintf("\n%s: write failed, %s inode limit reached\n",
                            ITOV(ip)->v_mount->mnt_stat.f_mntonname,
                            quotatypes[type]);
                        dq->dq_flags |= DQ_INODS;
                }
                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 = gettime() + ip->i_ump->um_itime[type];
                        if (DIP(ip, uid) == cred->cr_uid)
                                uprintf("\n%s: warning, %s %s\n",
                                    ITOV(ip)->v_mount->mnt_stat.f_mntonname,
                                    quotatypes[type], "inode quota exceeded");
                        return (0);
                }
                if (gettime() > dq->dq_itime) {
                        if ((dq->dq_flags & DQ_INODS) == 0 &&
                            DIP(ip, uid) == cred->cr_uid) {
                                uprintf("\n%s: write failed, %s %s\n",
                                    ITOV(ip)->v_mount->mnt_stat.f_mntonname,
                                    quotatypes[type],
                                    "inode quota exceeded for too long");
                                dq->dq_flags |= DQ_INODS;
                        }
                        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.
 */
void
chkdquot(struct inode *ip)
{
        struct ufsmount *ump = ip->i_ump;
        int i;
        struct vnode *vp = ITOV(ip);

        if (!VOP_ISLOCKED(vp)) 
                panic ("chkdquot: vnode is not locked");
                
        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) {
                        vprint("chkdquot: missing dquot", ITOV(ip));
                        panic("missing dquot");
                }
        }
}
#endif

/*
 * Code to process quotactl commands.
 */

int
quotaon_vnode(struct vnode *vp, void *arg) 
{
        int error;

        if (vp->v_type == VNON || vp->v_writecount == 0)
                return (0);

        if (vget(vp, LK_EXCLUSIVE)) {
                return (0);
        }

        error = getinoquota(VTOI(vp));
        vput(vp);
        
        return (error);
}

/*
 * Q_QUOTAON - set up a quota file for a particular file system.
 */
int
quotaon(struct proc *p, struct mount *mp, int type, caddr_t fname)
{
        struct ufsmount *ump = VFSTOUFS(mp);
        struct vnode *vp, **vpp;
        struct dquot *dq;
        int error;
        struct nameidata nd;

#ifdef DIAGNOSTIC
        if (!vfs_isbusy(mp))
                panic ("quotaon: mount point not busy");
#endif

        vpp = &ump->um_quotas[type];
        NDINIT(&nd, 0, 0, UIO_USERSPACE, fname, p);
        if ((error = vn_open(&nd, FREAD|FWRITE, 0)) != 0)
                return (error);
        vp = nd.ni_vp;
        VOP_UNLOCK(vp);
        if (vp->v_type != VREG) {
                (void) vn_close(vp, FREAD|FWRITE, p->p_ucred, p);
                return (EACCES);
        }

        /*
         * Update the vnode and ucred for quota file updates
         */
        if (*vpp != vp) {
                quotaoff(p, mp, type);
                *vpp = vp;
                crhold(p->p_ucred);
                ump->um_cred[type] = p->p_ucred;
        } else {
                struct ucred *ocred = ump->um_cred[type];

                (void) vn_close(vp, FREAD|FWRITE, ocred, p);
                if (ocred != p->p_ucred) {
                        crhold(p->p_ucred);
                        ump->um_cred[type] = p->p_ucred;
                        crfree(ocred);
                }
        }

        ump->um_qflags[type] |= QTF_OPENING;
        mp->mnt_flag |= MNT_QUOTA;
        vp->v_flag |= VSYSTEM;
        /*
         * Set up the time limits for this quota.
         */
        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.
         */
        error = vfs_mount_foreach_vnode(mp, quotaon_vnode, NULL);

        ump->um_qflags[type] &= ~QTF_OPENING;
        if (error)
                quotaoff(p, mp, type);
        return (error);
}

struct quotaoff_arg {
        struct proc *p;
        int type;
};

int
quotaoff_vnode(struct vnode *vp, void *arg) 
{
        struct quotaoff_arg *qa = (struct quotaoff_arg *)arg;
        struct inode *ip;
        struct dquot *dq;

        if (vp->v_type == VNON)
                return (0);

        if (vget(vp, LK_EXCLUSIVE))
                return (0);
        ip = VTOI(vp);
        dq = ip->i_dquot[qa->type];
        ip->i_dquot[qa->type] = NODQUOT;
        dqrele(vp, dq);
        vput(vp);
        return (0);
}

/*
 * Q_QUOTAOFF - turn off disk quotas for a filesystem.
 */
int
quotaoff(struct proc *p, struct mount *mp, int type)
{
        struct vnode *qvp;
        struct ufsmount *ump = VFSTOUFS(mp);
        struct quotaoff_arg qa;
        int error;
        
#ifdef DIAGNOSTIC
        if (!vfs_isbusy(mp))
                panic ("quotaoff: mount point not busy");
#endif
        if ((qvp = ump->um_quotas[type]) == NULL)
                return (0);
        ump->um_qflags[type] |= QTF_CLOSING;
        /*
         * Search vnodes associated with this mount point,
         * deleting any references to quota file being closed.
         */
        qa.p = p;
        qa.type = type;
        vfs_mount_foreach_vnode(mp, quotaoff_vnode, &qa);

        error = vn_close(qvp, FREAD|FWRITE, p->p_ucred, p);
        ump->um_quotas[type] = NULL;
        crfree(ump->um_cred[type]);
        ump->um_cred[type] = NOCRED;
        ump->um_qflags[type] &= ~QTF_CLOSING;
        for (type = 0; type < MAXQUOTAS; type++)
                if (ump->um_quotas[type] != NULL)
                        break;
        if (type == MAXQUOTAS)
                mp->mnt_flag &= ~MNT_QUOTA;
        return (error);
}

/*
 * Q_GETQUOTA - return current values in a dqblk structure.
 */
int
getquota(struct mount *mp, u_long id, int type, caddr_t addr)
{
        struct dquot *dq;
        int error;

        if ((error = dqget(NULL, id, VFSTOUFS(mp), type, &dq)) != 0)
                return (error);
        error = copyout((caddr_t)&dq->dq_dqb, addr, sizeof (struct dqblk));
#ifdef KTRACE
        if (error == 0) {
                struct proc *p = curproc;
                if (KTRPOINT(p, KTR_STRUCT))
                        ktrquota(p, &dq->dq_dqb);
        }
#endif

        dqrele(NULL, dq);
        return (error);
}

/*
 * Q_SETQUOTA - assign an entire dqblk structure.
 */
int
setquota(struct mount *mp, u_long id, int type, caddr_t addr)
{
        struct dquot *dq;
        struct dquot *ndq;
        struct ufsmount *ump = VFSTOUFS(mp);
        struct dqblk newlim;
        int error;

        error = copyin(addr, (caddr_t)&newlim, sizeof (struct dqblk));
        if (error)
                return (error);
#ifdef KTRACE
        {
                struct proc *p = curproc;
                if (KTRPOINT(p, KTR_STRUCT))
                        ktrquota(p, &newlim);
        }
#endif

        if ((error = dqget(NULL, id, ump, type, &ndq)) != 0)
                return (error);
        dq = ndq;
        while (dq->dq_flags & DQ_LOCK) {
                dq->dq_flags |= DQ_WANT;
                tsleep_nsec(dq, PINOD+1, "setquota", INFSLP);
        }
        /*
         * 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 = gettime() + 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 = gettime() + 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;
        dqrele(NULL, dq);
        return (0);
}

/*
 * Q_SETUSE - set current inode and block usage.
 */
int
setuse(struct mount *mp, u_long id, int type, caddr_t addr)
{
        struct dquot *dq;
        struct ufsmount *ump = VFSTOUFS(mp);
        struct dquot *ndq;
        struct dqblk usage;
        int error;

        error = copyin(addr, (caddr_t)&usage, sizeof (struct dqblk));
        if (error)
                return (error);
#ifdef KTRACE
        {
                struct proc *p = curproc;
                if (KTRPOINT(p, KTR_STRUCT))
                        ktrquota(p, &usage);
        }
#endif

        if ((error = dqget(NULL, id, ump, type, &ndq)) != 0)
                return (error);
        dq = ndq;
        while (dq->dq_flags & DQ_LOCK) {
                dq->dq_flags |= DQ_WANT;
                tsleep_nsec(dq, PINOD+1, "setuse", INFSLP);
        }
        /*
         * 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 = gettime() + ump->um_btime[type];
        if (dq->dq_isoftlimit && dq->dq_curinodes < dq->dq_isoftlimit &&
            usage.dqb_curinodes >= dq->dq_isoftlimit)
                dq->dq_itime = gettime() + 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;
        dqrele(NULL, dq);
        return (0);
}

int
qsync_vnode(struct vnode *vp, void *arg)
{
        int i;
        struct dquot *dq;
            
        if (vp->v_type == VNON)
                return (0);

        if (vget(vp, LK_EXCLUSIVE | LK_NOWAIT))
                return (0);

        for (i = 0; i < MAXQUOTAS; i++) {
                dq = VTOI(vp)->i_dquot[i];
                if (dq != NODQUOT && (dq->dq_flags & DQ_MOD))
                        dqsync(vp, dq);
        }
        vput(vp);
        return (0);
}

/*
 * Q_SYNC - sync quota files to disk.
 */
int
qsync(struct mount *mp)
{
        struct ufsmount *ump = VFSTOUFS(mp);
        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 vnodes associated with this mount point,
         * synchronizing any modified dquot structures.
         */
        vfs_mount_foreach_vnode(mp, qsync_vnode, NULL);
        return (0);
}

/*
 * Code pertaining to management of the in-core dquot data structures.
 */
LIST_HEAD(dqhash, dquot) *dqhashtbl;
SIPHASH_KEY dqhashkey;
u_long dqhash;

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

/*
 * Initialize the quota system.
 */
void
ufs_quota_init(void)
{
        dqhashtbl = hashinit(initialvnodes, M_DQUOT, M_WAITOK, &dqhash);
        arc4random_buf(&dqhashkey, sizeof(dqhashkey));
        TAILQ_INIT(&dqfreelist);
}

/*
 * Obtain a dquot structure for the specified identifier and quota file
 * reading the information from the file if necessary.
 */
int
dqget(struct vnode *vp, u_long id, struct ufsmount *ump, int type,
    struct dquot **dqp)
{
        SIPHASH_CTX ctx;
        struct dquot *dq;
        struct dqhash *dqh;
        struct vnode *dqvp;
        struct iovec aiov;
        struct uio auio;
        int error;

        dqvp = ump->um_quotas[type];
        if (dqvp == NULL || (ump->um_qflags[type] & QTF_CLOSING)) {
                *dqp = NODQUOT;
                return (EINVAL);
        }
        /*
         * Check the cache first.
         */
        SipHash24_Init(&ctx, &dqhashkey);
        SipHash24_Update(&ctx, &dqvp, sizeof(dqvp));
        SipHash24_Update(&ctx, &id, sizeof(id));
        dqh = &dqhashtbl[SipHash24_End(&ctx) & dqhash];

        LIST_FOREACH(dq, dqh, dq_hash) {
                if (dq->dq_id != id ||
                    dq->dq_vp != 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);
                *dqp = dq;
                return (0);
        }
        /*
         * Not in cache, allocate a new one.
         */
        if (TAILQ_FIRST(&dqfreelist) == NODQUOT &&
            numdquot < MAXQUOTAS * initialvnodes)
                desireddquot += DQUOTINC;
        if (numdquot < desireddquot) {
                dq = malloc(sizeof *dq, M_DQUOT, M_WAITOK | M_ZERO);
                numdquot++;
        } else {
                if ((dq = TAILQ_FIRST(&dqfreelist)) == NULL) {
                        tablefull("dquot");
                        *dqp = NODQUOT;
                        return (EUSERS);
                }
                if (dq->dq_cnt || (dq->dq_flags & DQ_MOD))
                        panic("free dquot isn't");
                TAILQ_REMOVE(&dqfreelist, dq, dq_freelist);
                LIST_REMOVE(dq, dq_hash);
                crfree(dq->dq_cred);
                dq->dq_cred = NOCRED;
        }
        /*
         * Initialize the contents of the dquot structure.
         */
        if (vp != dqvp)
                vn_lock(dqvp, LK_EXCLUSIVE | LK_RETRY);
        LIST_INSERT_HEAD(dqh, dq, dq_hash);
        dqref(dq);
        dq->dq_flags = DQ_LOCK;
        dq->dq_id = id;
        dq->dq_vp = dqvp;
        dq->dq_type = type;
        crhold(ump->um_cred[type]);
        dq->dq_cred = ump->um_cred[type];
        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        aiov.iov_base = (caddr_t)&dq->dq_dqb;
        aiov.iov_len = sizeof (struct dqblk);
        auio.uio_resid = sizeof (struct dqblk);
        auio.uio_offset = (off_t)(id * sizeof (struct dqblk));
        auio.uio_segflg = UIO_SYSSPACE;
        auio.uio_rw = UIO_READ;
        auio.uio_procp = NULL;
        error = VOP_READ(dqvp, &auio, 0, dq->dq_cred);
        if (auio.uio_resid == sizeof(struct dqblk) && error == 0)
                memset(&dq->dq_dqb, 0, sizeof(struct dqblk));
        if (vp != dqvp)
                VOP_UNLOCK(dqvp);
        if (dq->dq_flags & DQ_WANT)
                wakeup(dq);
        dq->dq_flags = 0;
        /*
         * I/O error in reading quota file, release
         * quota structure and reflect problem to caller.
         */
        if (error) {
                LIST_REMOVE(dq, dq_hash);
                dqrele(vp, dq);
                *dqp = NODQUOT;
                return (error);
        }
        /*
         * 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 = gettime() + ump->um_btime[type];
                if (dq->dq_itime == 0)
                        dq->dq_itime = gettime() + ump->um_itime[type];
        }
        *dqp = dq;
        return (0);
}

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

        if (dq == NODQUOT)
                return;
        if (dq->dq_cnt > 1) {
                dq->dq_cnt--;
                return;
        }
        if (dq->dq_flags & DQ_MOD)
                (void) dqsync(vp, dq);
        if (--dq->dq_cnt > 0)
                return;
        TAILQ_INSERT_TAIL(&dqfreelist, dq, dq_freelist);
}

/*
 * Update the disk quota in the quota file.
 */
int
dqsync(struct vnode *vp, struct dquot *dq)
{
        struct vnode *dqvp;
        struct iovec aiov;
        struct uio auio;
        int error;

        if (dq == NODQUOT)
                panic("dqsync: dquot");
        if ((dq->dq_flags & DQ_MOD) == 0)
                return (0);
        if ((dqvp = dq->dq_vp) == NULL)
                panic("dqsync: file");

        if (vp != dqvp)
                vn_lock(dqvp, LK_EXCLUSIVE | LK_RETRY);
        while (dq->dq_flags & DQ_LOCK) {
                dq->dq_flags |= DQ_WANT;
                tsleep_nsec(dq, PINOD+2, "dqsync", INFSLP);
                if ((dq->dq_flags & DQ_MOD) == 0) {
                        if (vp != dqvp)
                                VOP_UNLOCK(dqvp);
                        return (0);
                }
        }
        dq->dq_flags |= DQ_LOCK;
        auio.uio_iov = &aiov;
        auio.uio_iovcnt = 1;
        aiov.iov_base = (caddr_t)&dq->dq_dqb;
        aiov.iov_len = sizeof (struct dqblk);
        auio.uio_resid = sizeof (struct dqblk);
        auio.uio_offset = (off_t)(dq->dq_id * sizeof (struct dqblk));
        auio.uio_segflg = UIO_SYSSPACE;
        auio.uio_rw = UIO_WRITE;
        auio.uio_procp = NULL;
        error = VOP_WRITE(dqvp, &auio, 0, dq->dq_cred);
        if (auio.uio_resid && error == 0)
                error = EIO;
        if (dq->dq_flags & DQ_WANT)
                wakeup(dq);
        dq->dq_flags &= ~(DQ_MOD|DQ_LOCK|DQ_WANT);
        if (vp != dqvp)
                VOP_UNLOCK(dqvp);
        return (error);
}

int
ufs_quota_delete(struct inode *ip)
{
        struct vnode *vp = ITOV(ip);
        int i;
        for (i = 0; i < MAXQUOTAS; i++) {
                if (ip->i_dquot[i] != NODQUOT) {
                        dqrele(vp, ip->i_dquot[i]);
                        ip->i_dquot[i] = NODQUOT;
                }
        }

        return (0);
}

/*
 * Do operations associated with quotas
 */
int
ufs_quotactl(struct mount *mp, int cmds, uid_t uid, caddr_t arg,
    struct proc *p)
{
        int cmd, type, error;

        if (uid == -1)
                uid = p->p_ucred->cr_ruid;
        cmd = cmds >> SUBCMDSHIFT;

        switch (cmd) {
        case Q_SYNC:
                break;
        case Q_GETQUOTA:
                if (uid == p->p_ucred->cr_ruid)
                        break;
                /* FALLTHROUGH */
        default:
                if ((error = suser(p)) != 0)
                        return (error);
        }

        type = cmds & SUBCMDMASK;
        if ((u_int)type >= MAXQUOTAS)
                return (EINVAL);

        if (vfs_busy(mp, VB_READ|VB_NOWAIT))
                return (0);
 

        switch (cmd) {

        case Q_QUOTAON:
                error = quotaon(p, mp, type, arg);
                break;

        case Q_QUOTAOFF:
                error = quotaoff(p, mp, type);
                break;

        case Q_SETQUOTA:
                error = setquota(mp, uid, type, arg) ;
                break;

        case Q_SETUSE:
                error = setuse(mp, uid, type, arg);
                break;

        case Q_GETQUOTA:
                error = getquota(mp, uid, type, arg);
                break;

        case Q_SYNC:
                error = qsync(mp);
                break;

        default:
                error = EINVAL;
                break;
        }

        vfs_unbusy(mp);
        return (error);
}