/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_sb.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_ialloc.h"
#include "xfs_itable.h"
#include "xfs_quota.h"
#include "xfs_error.h"
#include "xfs_bmap.h"
#include "xfs_bmap_btree.h"
#include "xfs_trans.h"
#include "xfs_trans_space.h"
#include "xfs_qm.h"
#include "xfs_trace.h"
#include "xfs_icache.h"
#include "xfs_cksum.h"

/*
 * The global quota manager. There is only one of these for the entire
 * system, _not_ one per file system. XQM keeps track of the overall
 * quota functionality, including maintaining the freelist and hash
 * tables of dquots.
 */
STATIC int      xfs_qm_init_quotainos(xfs_mount_t *);
STATIC int      xfs_qm_init_quotainfo(xfs_mount_t *);


STATIC void     xfs_qm_dqfree_one(struct xfs_dquot *dqp);
/*
 * We use the batch lookup interface to iterate over the dquots as it
 * currently is the only interface into the radix tree code that allows
 * fuzzy lookups instead of exact matches.  Holding the lock over multiple
 * operations is fine as all callers are used either during mount/umount
 * or quotaoff.
 */
#define XFS_DQ_LOOKUP_BATCH     32

STATIC int
xfs_qm_dquot_walk(
        struct xfs_mount        *mp,
        int                     type,
        int                     (*execute)(struct xfs_dquot *dqp, void *data),
        void                    *data)
{
        struct xfs_quotainfo    *qi = mp->m_quotainfo;
        struct radix_tree_root  *tree = xfs_dquot_tree(qi, type);
        uint32_t                next_index;
        int                     last_error = 0;
        int                     skipped;
        int                     nr_found;

restart:
        skipped = 0;
        next_index = 0;
        nr_found = 0;

        while (1) {
                struct xfs_dquot *batch[XFS_DQ_LOOKUP_BATCH];
                int             error = 0;
                int             i;

                mutex_lock(&qi->qi_tree_lock);
                nr_found = radix_tree_gang_lookup(tree, (void **)batch,
                                        next_index, XFS_DQ_LOOKUP_BATCH);
                if (!nr_found) {
                        mutex_unlock(&qi->qi_tree_lock);
                        break;
                }

                for (i = 0; i < nr_found; i++) {
                        struct xfs_dquot *dqp = batch[i];

                        next_index = be32_to_cpu(dqp->q_core.d_id) + 1;

                        error = execute(batch[i], data);
                        if (error == -EAGAIN) {
                                skipped++;
                                continue;
                        }
                        if (error && last_error != -EFSCORRUPTED)
                                last_error = error;
                }

                mutex_unlock(&qi->qi_tree_lock);

                /* bail out if the filesystem is corrupted.  */
                if (last_error == -EFSCORRUPTED) {
                        skipped = 0;
                        break;
                }
        }

        if (skipped) {
                delay(1);
                goto restart;
        }

        return last_error;
}


/*
 * Purge a dquot from all tracking data structures and free it.
 */
STATIC int
xfs_qm_dqpurge(
        struct xfs_dquot        *dqp,
        void                    *data)
{
        struct xfs_mount        *mp = dqp->q_mount;
        struct xfs_quotainfo    *qi = mp->m_quotainfo;

        xfs_dqlock(dqp);
        if ((dqp->dq_flags & XFS_DQ_FREEING) || dqp->q_nrefs != 0) {
                xfs_dqunlock(dqp);
                return -EAGAIN;
        }

        dqp->dq_flags |= XFS_DQ_FREEING;

        xfs_dqflock(dqp);

        /*
         * If we are turning this type of quotas off, we don't care
         * about the dirty metadata sitting in this dquot. OTOH, if
         * we're unmounting, we do care, so we flush it and wait.
         */
        if (XFS_DQ_IS_DIRTY(dqp)) {
                struct xfs_buf  *bp = NULL;
                int             error;

                /*
                 * We don't care about getting disk errors here. We need
                 * to purge this dquot anyway, so we go ahead regardless.
                 */
                error = xfs_qm_dqflush(dqp, &bp);
                if (error) {
                        xfs_warn(mp, "%s: dquot %p flush failed",
                                __func__, dqp);
                } else {
                        error = xfs_bwrite(bp);
                        xfs_buf_relse(bp);
                }
                xfs_dqflock(dqp);
        }

        ASSERT(atomic_read(&dqp->q_pincount) == 0);
        ASSERT(XFS_FORCED_SHUTDOWN(mp) ||
               !(dqp->q_logitem.qli_item.li_flags & XFS_LI_IN_AIL));

        xfs_dqfunlock(dqp);
        xfs_dqunlock(dqp);

        radix_tree_delete(xfs_dquot_tree(qi, dqp->q_core.d_flags),
                          be32_to_cpu(dqp->q_core.d_id));
        qi->qi_dquots--;

        /*
         * We move dquots to the freelist as soon as their reference count
         * hits zero, so it really should be on the freelist here.
         */
        ASSERT(!list_empty(&dqp->q_lru));
        list_lru_del(&qi->qi_lru, &dqp->q_lru);
        XFS_STATS_DEC(mp, xs_qm_dquot_unused);

        xfs_qm_dqdestroy(dqp);
        return 0;
}

/*
 * Purge the dquot cache.
 */
void
xfs_qm_dqpurge_all(
        struct xfs_mount        *mp,
        uint                    flags)
{
        if (flags & XFS_QMOPT_UQUOTA)
                xfs_qm_dquot_walk(mp, XFS_DQ_USER, xfs_qm_dqpurge, NULL);
        if (flags & XFS_QMOPT_GQUOTA)
                xfs_qm_dquot_walk(mp, XFS_DQ_GROUP, xfs_qm_dqpurge, NULL);
        if (flags & XFS_QMOPT_PQUOTA)
                xfs_qm_dquot_walk(mp, XFS_DQ_PROJ, xfs_qm_dqpurge, NULL);
}

/*
 * Just destroy the quotainfo structure.
 */
void
xfs_qm_unmount(
        struct xfs_mount        *mp)
{
        if (mp->m_quotainfo) {
                xfs_qm_dqpurge_all(mp, XFS_QMOPT_QUOTALL);
                xfs_qm_destroy_quotainfo(mp);
        }
}

/*
 * Called from the vfsops layer.
 */
void
xfs_qm_unmount_quotas(
        xfs_mount_t     *mp)
{
        /*
         * Release the dquots that root inode, et al might be holding,
         * before we flush quotas and blow away the quotainfo structure.
         */
        ASSERT(mp->m_rootip);
        xfs_qm_dqdetach(mp->m_rootip);
        if (mp->m_rbmip)
                xfs_qm_dqdetach(mp->m_rbmip);
        if (mp->m_rsumip)
                xfs_qm_dqdetach(mp->m_rsumip);

        /*
         * Release the quota inodes.
         */
        if (mp->m_quotainfo) {
                if (mp->m_quotainfo->qi_uquotaip) {
                        IRELE(mp->m_quotainfo->qi_uquotaip);
                        mp->m_quotainfo->qi_uquotaip = NULL;
                }
                if (mp->m_quotainfo->qi_gquotaip) {
                        IRELE(mp->m_quotainfo->qi_gquotaip);
                        mp->m_quotainfo->qi_gquotaip = NULL;
                }
                if (mp->m_quotainfo->qi_pquotaip) {
                        IRELE(mp->m_quotainfo->qi_pquotaip);
                        mp->m_quotainfo->qi_pquotaip = NULL;
                }
        }
}

STATIC int
xfs_qm_dqattach_one(
        xfs_inode_t     *ip,
        xfs_dqid_t      id,
        uint            type,
        uint            doalloc,
        xfs_dquot_t     **IO_idqpp)
{
        xfs_dquot_t     *dqp;
        int             error;

        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
        error = 0;

        /*
         * See if we already have it in the inode itself. IO_idqpp is &i_udquot
         * or &i_gdquot. This made the code look weird, but made the logic a lot
         * simpler.
         */
        dqp = *IO_idqpp;
        if (dqp) {
                trace_xfs_dqattach_found(dqp);
                return 0;
        }

        /*
         * Find the dquot from somewhere. This bumps the reference count of
         * dquot and returns it locked.  This can return ENOENT if dquot didn't
         * exist on disk and we didn't ask it to allocate; ESRCH if quotas got
         * turned off suddenly.
         */
        error = xfs_qm_dqget(ip->i_mount, ip, id, type,
                             doalloc | XFS_QMOPT_DOWARN, &dqp);
        if (error)
                return error;

        trace_xfs_dqattach_get(dqp);

        /*
         * dqget may have dropped and re-acquired the ilock, but it guarantees
         * that the dquot returned is the one that should go in the inode.
         */
        *IO_idqpp = dqp;
        xfs_dqunlock(dqp);
        return 0;
}

static bool
xfs_qm_need_dqattach(
        struct xfs_inode        *ip)
{
        struct xfs_mount        *mp = ip->i_mount;

        if (!XFS_IS_QUOTA_RUNNING(mp))
                return false;
        if (!XFS_IS_QUOTA_ON(mp))
                return false;
        if (!XFS_NOT_DQATTACHED(mp, ip))
                return false;
        if (xfs_is_quota_inode(&mp->m_sb, ip->i_ino))
                return false;
        return true;
}

/*
 * Given a locked inode, attach dquot(s) to it, taking U/G/P-QUOTAON
 * into account.
 * If XFS_QMOPT_DQALLOC, the dquot(s) will be allocated if needed.
 * Inode may get unlocked and relocked in here, and the caller must deal with
 * the consequences.
 */
int
xfs_qm_dqattach_locked(
        xfs_inode_t     *ip,
        uint            flags)
{
        xfs_mount_t     *mp = ip->i_mount;
        int             error = 0;

        if (!xfs_qm_need_dqattach(ip))
                return 0;

        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));

        if (XFS_IS_UQUOTA_ON(mp) && !ip->i_udquot) {
                error = xfs_qm_dqattach_one(ip, ip->i_d.di_uid, XFS_DQ_USER,
                                                flags & XFS_QMOPT_DQALLOC,
                                                &ip->i_udquot);
                if (error)
                        goto done;
                ASSERT(ip->i_udquot);
        }

        if (XFS_IS_GQUOTA_ON(mp) && !ip->i_gdquot) {
                error = xfs_qm_dqattach_one(ip, ip->i_d.di_gid, XFS_DQ_GROUP,
                                                flags & XFS_QMOPT_DQALLOC,
                                                &ip->i_gdquot);
                if (error)
                        goto done;
                ASSERT(ip->i_gdquot);
        }

        if (XFS_IS_PQUOTA_ON(mp) && !ip->i_pdquot) {
                error = xfs_qm_dqattach_one(ip, xfs_get_projid(ip), XFS_DQ_PROJ,
                                                flags & XFS_QMOPT_DQALLOC,
                                                &ip->i_pdquot);
                if (error)
                        goto done;
                ASSERT(ip->i_pdquot);
        }

done:
        /*
         * Don't worry about the dquots that we may have attached before any
         * error - they'll get detached later if it has not already been done.
         */
        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
        return error;
}

int
xfs_qm_dqattach(
        struct xfs_inode        *ip,
        uint                    flags)
{
        int                     error;

        if (!xfs_qm_need_dqattach(ip))
                return 0;

        xfs_ilock(ip, XFS_ILOCK_EXCL);
        error = xfs_qm_dqattach_locked(ip, flags);
        xfs_iunlock(ip, XFS_ILOCK_EXCL);

        return error;
}

/*
 * Release dquots (and their references) if any.
 * The inode should be locked EXCL except when this's called by
 * xfs_ireclaim.
 */
void
xfs_qm_dqdetach(
        xfs_inode_t     *ip)
{
        if (!(ip->i_udquot || ip->i_gdquot || ip->i_pdquot))
                return;

        trace_xfs_dquot_dqdetach(ip);

        ASSERT(!xfs_is_quota_inode(&ip->i_mount->m_sb, ip->i_ino));
        if (ip->i_udquot) {
                xfs_qm_dqrele(ip->i_udquot);
                ip->i_udquot = NULL;
        }
        if (ip->i_gdquot) {
                xfs_qm_dqrele(ip->i_gdquot);
                ip->i_gdquot = NULL;
        }
        if (ip->i_pdquot) {
                xfs_qm_dqrele(ip->i_pdquot);
                ip->i_pdquot = NULL;
        }
}

struct xfs_qm_isolate {
        struct list_head        buffers;
        struct list_head        dispose;
};

static enum lru_status
xfs_qm_dquot_isolate(
        struct list_head        *item,
        struct list_lru_one     *lru,
        spinlock_t              *lru_lock,
        void                    *arg)
                __releases(lru_lock) __acquires(lru_lock)
{
        struct xfs_dquot        *dqp = container_of(item,
                                                struct xfs_dquot, q_lru);
        struct xfs_qm_isolate   *isol = arg;

        if (!xfs_dqlock_nowait(dqp))
                goto out_miss_busy;

        /*
         * This dquot has acquired a reference in the meantime remove it from
         * the freelist and try again.
         */
        if (dqp->q_nrefs) {
                xfs_dqunlock(dqp);
                XFS_STATS_INC(dqp->q_mount, xs_qm_dqwants);

                trace_xfs_dqreclaim_want(dqp);
                list_lru_isolate(lru, &dqp->q_lru);
                XFS_STATS_DEC(dqp->q_mount, xs_qm_dquot_unused);
                return LRU_REMOVED;
        }

        /*
         * If the dquot is dirty, flush it. If it's already being flushed, just
         * skip it so there is time for the IO to complete before we try to
         * reclaim it again on the next LRU pass.
         */
        if (!xfs_dqflock_nowait(dqp)) {
                xfs_dqunlock(dqp);
                goto out_miss_busy;
        }

        if (XFS_DQ_IS_DIRTY(dqp)) {
                struct xfs_buf  *bp = NULL;
                int             error;

                trace_xfs_dqreclaim_dirty(dqp);

                /* we have to drop the LRU lock to flush the dquot */
                spin_unlock(lru_lock);

                error = xfs_qm_dqflush(dqp, &bp);
                if (error) {
                        xfs_warn(dqp->q_mount, "%s: dquot %p flush failed",
                                 __func__, dqp);
                        goto out_unlock_dirty;
                }

                xfs_buf_delwri_queue(bp, &isol->buffers);
                xfs_buf_relse(bp);
                goto out_unlock_dirty;
        }
        xfs_dqfunlock(dqp);

        /*
         * Prevent lookups now that we are past the point of no return.
         */
        dqp->dq_flags |= XFS_DQ_FREEING;
        xfs_dqunlock(dqp);

        ASSERT(dqp->q_nrefs == 0);
        list_lru_isolate_move(lru, &dqp->q_lru, &isol->dispose);
        XFS_STATS_DEC(dqp->q_mount, xs_qm_dquot_unused);
        trace_xfs_dqreclaim_done(dqp);
        XFS_STATS_INC(dqp->q_mount, xs_qm_dqreclaims);
        return LRU_REMOVED;

out_miss_busy:
        trace_xfs_dqreclaim_busy(dqp);
        XFS_STATS_INC(dqp->q_mount, xs_qm_dqreclaim_misses);
        return LRU_SKIP;

out_unlock_dirty:
        trace_xfs_dqreclaim_busy(dqp);
        XFS_STATS_INC(dqp->q_mount, xs_qm_dqreclaim_misses);
        xfs_dqunlock(dqp);
        spin_lock(lru_lock);
        return LRU_RETRY;
}

static unsigned long
xfs_qm_shrink_scan(
        struct shrinker         *shrink,
        struct shrink_control   *sc)
{
        struct xfs_quotainfo    *qi = container_of(shrink,
                                        struct xfs_quotainfo, qi_shrinker);
        struct xfs_qm_isolate   isol;
        unsigned long           freed;
        int                     error;

        if ((sc->gfp_mask & (__GFP_FS|__GFP_DIRECT_RECLAIM)) != (__GFP_FS|__GFP_DIRECT_RECLAIM))
                return 0;

        INIT_LIST_HEAD(&isol.buffers);
        INIT_LIST_HEAD(&isol.dispose);

        freed = list_lru_shrink_walk(&qi->qi_lru, sc,
                                     xfs_qm_dquot_isolate, &isol);

        error = xfs_buf_delwri_submit(&isol.buffers);
        if (error)
                xfs_warn(NULL, "%s: dquot reclaim failed", __func__);

        while (!list_empty(&isol.dispose)) {
                struct xfs_dquot        *dqp;

                dqp = list_first_entry(&isol.dispose, struct xfs_dquot, q_lru);
                list_del_init(&dqp->q_lru);
                xfs_qm_dqfree_one(dqp);
        }

        return freed;
}

static unsigned long
xfs_qm_shrink_count(
        struct shrinker         *shrink,
        struct shrink_control   *sc)
{
        struct xfs_quotainfo    *qi = container_of(shrink,
                                        struct xfs_quotainfo, qi_shrinker);

        return list_lru_shrink_count(&qi->qi_lru, sc);
}

STATIC void
xfs_qm_set_defquota(
        xfs_mount_t     *mp,
        uint            type,
        xfs_quotainfo_t *qinf)
{
        xfs_dquot_t             *dqp;
        struct xfs_def_quota    *defq;
        int                     error;

        error = xfs_qm_dqread(mp, 0, type, XFS_QMOPT_DOWARN, &dqp);

        if (!error) {
                xfs_disk_dquot_t        *ddqp = &dqp->q_core;

                defq = xfs_get_defquota(dqp, qinf);

                /*
                 * Timers and warnings have been already set, let's just set the
                 * default limits for this quota type
                 */
                defq->bhardlimit = be64_to_cpu(ddqp->d_blk_hardlimit);
                defq->bsoftlimit = be64_to_cpu(ddqp->d_blk_softlimit);
                defq->ihardlimit = be64_to_cpu(ddqp->d_ino_hardlimit);
                defq->isoftlimit = be64_to_cpu(ddqp->d_ino_softlimit);
                defq->rtbhardlimit = be64_to_cpu(ddqp->d_rtb_hardlimit);
                defq->rtbsoftlimit = be64_to_cpu(ddqp->d_rtb_softlimit);
                xfs_qm_dqdestroy(dqp);
        }
}

/*
 * This initializes all the quota information that's kept in the
 * mount structure
 */
STATIC int
xfs_qm_init_quotainfo(
        xfs_mount_t     *mp)
{
        xfs_quotainfo_t *qinf;
        int             error;
        xfs_dquot_t     *dqp;

        ASSERT(XFS_IS_QUOTA_RUNNING(mp));

        qinf = mp->m_quotainfo = kmem_zalloc(sizeof(xfs_quotainfo_t), KM_SLEEP);

        error = list_lru_init(&qinf->qi_lru);
        if (error)
                goto out_free_qinf;

        /*
         * See if quotainodes are setup, and if not, allocate them,
         * and change the superblock accordingly.
         */
        error = xfs_qm_init_quotainos(mp);
        if (error)
                goto out_free_lru;

        INIT_RADIX_TREE(&qinf->qi_uquota_tree, GFP_NOFS);
        INIT_RADIX_TREE(&qinf->qi_gquota_tree, GFP_NOFS);
        INIT_RADIX_TREE(&qinf->qi_pquota_tree, GFP_NOFS);
        mutex_init(&qinf->qi_tree_lock);

        /* mutex used to serialize quotaoffs */
        mutex_init(&qinf->qi_quotaofflock);

        /* Precalc some constants */
        qinf->qi_dqchunklen = XFS_FSB_TO_BB(mp, XFS_DQUOT_CLUSTER_SIZE_FSB);
        qinf->qi_dqperchunk = xfs_calc_dquots_per_chunk(qinf->qi_dqchunklen);

        mp->m_qflags |= (mp->m_sb.sb_qflags & XFS_ALL_QUOTA_CHKD);

        /*
         * We try to get the limits from the superuser's limits fields.
         * This is quite hacky, but it is standard quota practice.
         *
         * Since we may not have done a quotacheck by this point, just read
         * the dquot without attaching it to any hashtables or lists.
         *
         * Timers and warnings are globally set by the first timer found in
         * user/group/proj quota types, otherwise a default value is used.
         * This should be split into different fields per quota type.
         */
        error = xfs_qm_dqread(mp, 0,
                        XFS_IS_UQUOTA_RUNNING(mp) ? XFS_DQ_USER :
                         (XFS_IS_GQUOTA_RUNNING(mp) ? XFS_DQ_GROUP :
                          XFS_DQ_PROJ),
                        XFS_QMOPT_DOWARN, &dqp);

        if (!error) {
                xfs_disk_dquot_t        *ddqp = &dqp->q_core;

                /*
                 * The warnings and timers set the grace period given to
                 * a user or group before he or she can not perform any
                 * more writing. If it is zero, a default is used.
                 */
                qinf->qi_btimelimit = ddqp->d_btimer ?
                        be32_to_cpu(ddqp->d_btimer) : XFS_QM_BTIMELIMIT;
                qinf->qi_itimelimit = ddqp->d_itimer ?
                        be32_to_cpu(ddqp->d_itimer) : XFS_QM_ITIMELIMIT;
                qinf->qi_rtbtimelimit = ddqp->d_rtbtimer ?
                        be32_to_cpu(ddqp->d_rtbtimer) : XFS_QM_RTBTIMELIMIT;
                qinf->qi_bwarnlimit = ddqp->d_bwarns ?
                        be16_to_cpu(ddqp->d_bwarns) : XFS_QM_BWARNLIMIT;
                qinf->qi_iwarnlimit = ddqp->d_iwarns ?
                        be16_to_cpu(ddqp->d_iwarns) : XFS_QM_IWARNLIMIT;
                qinf->qi_rtbwarnlimit = ddqp->d_rtbwarns ?
                        be16_to_cpu(ddqp->d_rtbwarns) : XFS_QM_RTBWARNLIMIT;
                xfs_qm_dqdestroy(dqp);
        } else {
                qinf->qi_btimelimit = XFS_QM_BTIMELIMIT;
                qinf->qi_itimelimit = XFS_QM_ITIMELIMIT;
                qinf->qi_rtbtimelimit = XFS_QM_RTBTIMELIMIT;
                qinf->qi_bwarnlimit = XFS_QM_BWARNLIMIT;
                qinf->qi_iwarnlimit = XFS_QM_IWARNLIMIT;
                qinf->qi_rtbwarnlimit = XFS_QM_RTBWARNLIMIT;
        }

        if (XFS_IS_UQUOTA_RUNNING(mp))
                xfs_qm_set_defquota(mp, XFS_DQ_USER, qinf);
        if (XFS_IS_GQUOTA_RUNNING(mp))
                xfs_qm_set_defquota(mp, XFS_DQ_GROUP, qinf);
        if (XFS_IS_PQUOTA_RUNNING(mp))
                xfs_qm_set_defquota(mp, XFS_DQ_PROJ, qinf);

        qinf->qi_shrinker.count_objects = xfs_qm_shrink_count;
        qinf->qi_shrinker.scan_objects = xfs_qm_shrink_scan;
        qinf->qi_shrinker.seeks = DEFAULT_SEEKS;
        qinf->qi_shrinker.flags = SHRINKER_NUMA_AWARE;
        register_shrinker(&qinf->qi_shrinker);
        return 0;

out_free_lru:
        list_lru_destroy(&qinf->qi_lru);
out_free_qinf:
        kmem_free(qinf);
        mp->m_quotainfo = NULL;
        return error;
}


/*
 * Gets called when unmounting a filesystem or when all quotas get
 * turned off.
 * This purges the quota inodes, destroys locks and frees itself.
 */
void
xfs_qm_destroy_quotainfo(
        xfs_mount_t     *mp)
{
        xfs_quotainfo_t *qi;

        qi = mp->m_quotainfo;
        ASSERT(qi != NULL);

        unregister_shrinker(&qi->qi_shrinker);
        list_lru_destroy(&qi->qi_lru);

        if (qi->qi_uquotaip) {
                IRELE(qi->qi_uquotaip);
                qi->qi_uquotaip = NULL; /* paranoia */
        }
        if (qi->qi_gquotaip) {
                IRELE(qi->qi_gquotaip);
                qi->qi_gquotaip = NULL;
        }
        if (qi->qi_pquotaip) {
                IRELE(qi->qi_pquotaip);
                qi->qi_pquotaip = NULL;
        }
        mutex_destroy(&qi->qi_quotaofflock);
        kmem_free(qi);
        mp->m_quotainfo = NULL;
}

/*
 * Create an inode and return with a reference already taken, but unlocked
 * This is how we create quota inodes
 */
STATIC int
xfs_qm_qino_alloc(
        xfs_mount_t     *mp,
        xfs_inode_t     **ip,
        uint            flags)
{
        xfs_trans_t     *tp;
        int             error;
        int             committed;
        bool            need_alloc = true;

        *ip = NULL;
        /*
         * With superblock that doesn't have separate pquotino, we
         * share an inode between gquota and pquota. If the on-disk
         * superblock has GQUOTA and the filesystem is now mounted
         * with PQUOTA, just use sb_gquotino for sb_pquotino and
         * vice-versa.
         */
        if (!xfs_sb_version_has_pquotino(&mp->m_sb) &&
                        (flags & (XFS_QMOPT_PQUOTA|XFS_QMOPT_GQUOTA))) {
                xfs_ino_t ino = NULLFSINO;

                if ((flags & XFS_QMOPT_PQUOTA) &&
                             (mp->m_sb.sb_gquotino != NULLFSINO)) {
                        ino = mp->m_sb.sb_gquotino;
                        ASSERT(mp->m_sb.sb_pquotino == NULLFSINO);
                } else if ((flags & XFS_QMOPT_GQUOTA) &&
                             (mp->m_sb.sb_pquotino != NULLFSINO)) {
                        ino = mp->m_sb.sb_pquotino;
                        ASSERT(mp->m_sb.sb_gquotino == NULLFSINO);
                }
                if (ino != NULLFSINO) {
                        error = xfs_iget(mp, NULL, ino, 0, 0, ip);
                        if (error)
                                return error;
                        mp->m_sb.sb_gquotino = NULLFSINO;
                        mp->m_sb.sb_pquotino = NULLFSINO;
                        need_alloc = false;
                }
        }

        tp = xfs_trans_alloc(mp, XFS_TRANS_QM_QINOCREATE);
        error = xfs_trans_reserve(tp, &M_RES(mp)->tr_create,
                                  XFS_QM_QINOCREATE_SPACE_RES(mp), 0);
        if (error) {
                xfs_trans_cancel(tp);
                return error;
        }

        if (need_alloc) {
                error = xfs_dir_ialloc(&tp, NULL, S_IFREG, 1, 0, 0, 1, ip,
                                                                &committed);
                if (error) {
                        xfs_trans_cancel(tp);
                        return error;
                }
        }

        /*
         * Make the changes in the superblock, and log those too.
         * sbfields arg may contain fields other than *QUOTINO;
         * VERSIONNUM for example.
         */
        spin_lock(&mp->m_sb_lock);
        if (flags & XFS_QMOPT_SBVERSION) {
                ASSERT(!xfs_sb_version_hasquota(&mp->m_sb));

                xfs_sb_version_addquota(&mp->m_sb);
                mp->m_sb.sb_uquotino = NULLFSINO;
                mp->m_sb.sb_gquotino = NULLFSINO;
                mp->m_sb.sb_pquotino = NULLFSINO;

                /* qflags will get updated fully _after_ quotacheck */
                mp->m_sb.sb_qflags = mp->m_qflags & XFS_ALL_QUOTA_ACCT;
        }
        if (flags & XFS_QMOPT_UQUOTA)
                mp->m_sb.sb_uquotino = (*ip)->i_ino;
        else if (flags & XFS_QMOPT_GQUOTA)
                mp->m_sb.sb_gquotino = (*ip)->i_ino;
        else
                mp->m_sb.sb_pquotino = (*ip)->i_ino;
        spin_unlock(&mp->m_sb_lock);
        xfs_log_sb(tp);

        error = xfs_trans_commit(tp);
        if (error) {
                ASSERT(XFS_FORCED_SHUTDOWN(mp));
                xfs_alert(mp, "%s failed (error %d)!", __func__, error);
        }
        if (need_alloc)
                xfs_finish_inode_setup(*ip);
        return error;
}


STATIC void
xfs_qm_reset_dqcounts(
        xfs_mount_t     *mp,
        xfs_buf_t       *bp,
        xfs_dqid_t      id,
        uint            type)
{
        struct xfs_dqblk        *dqb;
        int                     j;

        trace_xfs_reset_dqcounts(bp, _RET_IP_);

        /*
         * Reset all counters and timers. They'll be
         * started afresh by xfs_qm_quotacheck.
         */
#ifdef DEBUG
        j = XFS_FSB_TO_B(mp, XFS_DQUOT_CLUSTER_SIZE_FSB);
        do_div(j, sizeof(xfs_dqblk_t));
        ASSERT(mp->m_quotainfo->qi_dqperchunk == j);
#endif
        dqb = bp->b_addr;
        for (j = 0; j < mp->m_quotainfo->qi_dqperchunk; j++) {
                struct xfs_disk_dquot   *ddq;

                ddq = (struct xfs_disk_dquot *)&dqb[j];

                /*
                 * Do a sanity check, and if needed, repair the dqblk. Don't
                 * output any warnings because it's perfectly possible to
                 * find uninitialised dquot blks. See comment in xfs_dqcheck.
                 */
                xfs_dqcheck(mp, ddq, id+j, type, XFS_QMOPT_DQREPAIR,
                            "xfs_quotacheck");
                /*
                 * Reset type in case we are reusing group quota file for
                 * project quotas or vice versa
                 */
                ddq->d_flags = type;
                ddq->d_bcount = 0;
                ddq->d_icount = 0;
                ddq->d_rtbcount = 0;
                ddq->d_btimer = 0;
                ddq->d_itimer = 0;
                ddq->d_rtbtimer = 0;
                ddq->d_bwarns = 0;
                ddq->d_iwarns = 0;
                ddq->d_rtbwarns = 0;

                if (xfs_sb_version_hascrc(&mp->m_sb)) {
                        xfs_update_cksum((char *)&dqb[j],
                                         sizeof(struct xfs_dqblk),
                                         XFS_DQUOT_CRC_OFF);
                }
        }
}

STATIC int
xfs_qm_dqiter_bufs(
        struct xfs_mount        *mp,
        xfs_dqid_t              firstid,
        xfs_fsblock_t           bno,
        xfs_filblks_t           blkcnt,
        uint                    flags,
        struct list_head        *buffer_list)
{
        struct xfs_buf          *bp;
        int                     error;
        int                     type;

        ASSERT(blkcnt > 0);
        type = flags & XFS_QMOPT_UQUOTA ? XFS_DQ_USER :
                (flags & XFS_QMOPT_PQUOTA ? XFS_DQ_PROJ : XFS_DQ_GROUP);
        error = 0;

        /*
         * Blkcnt arg can be a very big number, and might even be
         * larger than the log itself. So, we have to break it up into
         * manageable-sized transactions.
         * Note that we don't start a permanent transaction here; we might
         * not be able to get a log reservation for the whole thing up front,
         * and we don't really care to either, because we just discard
         * everything if we were to crash in the middle of this loop.
         */
        while (blkcnt--) {
                error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp,
                              XFS_FSB_TO_DADDR(mp, bno),
                              mp->m_quotainfo->qi_dqchunklen, 0, &bp,
                              &xfs_dquot_buf_ops);

                /*
                 * CRC and validation errors will return a EFSCORRUPTED here. If
                 * this occurs, re-read without CRC validation so that we can
                 * repair the damage via xfs_qm_reset_dqcounts(). This process
                 * will leave a trace in the log indicating corruption has
                 * been detected.
                 */
                if (error == -EFSCORRUPTED) {
                        error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp,
                                      XFS_FSB_TO_DADDR(mp, bno),
                                      mp->m_quotainfo->qi_dqchunklen, 0, &bp,
                                      NULL);
                }

                if (error)
                        break;

                /*
                 * A corrupt buffer might not have a verifier attached, so
                 * make sure we have the correct one attached before writeback
                 * occurs.
                 */
                bp->b_ops = &xfs_dquot_buf_ops;
                xfs_qm_reset_dqcounts(mp, bp, firstid, type);
                xfs_buf_delwri_queue(bp, buffer_list);
                xfs_buf_relse(bp);

                /* goto the next block. */
                bno++;
                firstid += mp->m_quotainfo->qi_dqperchunk;
        }

        return error;
}

/*
 * Iterate over all allocated USR/GRP/PRJ dquots in the system, calling a
 * caller supplied function for every chunk of dquots that we find.
 */
STATIC int
xfs_qm_dqiterate(
        struct xfs_mount        *mp,
        struct xfs_inode        *qip,
        uint                    flags,
        struct list_head        *buffer_list)
{
        struct xfs_bmbt_irec    *map;
        int                     i, nmaps;       /* number of map entries */
        int                     error;          /* return value */
        xfs_fileoff_t           lblkno;
        xfs_filblks_t           maxlblkcnt;
        xfs_dqid_t              firstid;
        xfs_fsblock_t           rablkno;
        xfs_filblks_t           rablkcnt;

        error = 0;
        /*
         * This looks racy, but we can't keep an inode lock across a
         * trans_reserve. But, this gets called during quotacheck, and that
         * happens only at mount time which is single threaded.
         */
        if (qip->i_d.di_nblocks == 0)
                return 0;

        map = kmem_alloc(XFS_DQITER_MAP_SIZE * sizeof(*map), KM_SLEEP);

        lblkno = 0;
        maxlblkcnt = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
        do {
                uint            lock_mode;

                nmaps = XFS_DQITER_MAP_SIZE;
                /*
                 * We aren't changing the inode itself. Just changing
                 * some of its data. No new blocks are added here, and
                 * the inode is never added to the transaction.
                 */
                lock_mode = xfs_ilock_data_map_shared(qip);
                error = xfs_bmapi_read(qip, lblkno, maxlblkcnt - lblkno,
                                       map, &nmaps, 0);
                xfs_iunlock(qip, lock_mode);
                if (error)
                        break;

                ASSERT(nmaps <= XFS_DQITER_MAP_SIZE);
                for (i = 0; i < nmaps; i++) {
                        ASSERT(map[i].br_startblock != DELAYSTARTBLOCK);
                        ASSERT(map[i].br_blockcount);


                        lblkno += map[i].br_blockcount;

                        if (map[i].br_startblock == HOLESTARTBLOCK)
                                continue;

                        firstid = (xfs_dqid_t) map[i].br_startoff *
                                mp->m_quotainfo->qi_dqperchunk;
                        /*
                         * Do a read-ahead on the next extent.
                         */
                        if ((i+1 < nmaps) &&
                            (map[i+1].br_startblock != HOLESTARTBLOCK)) {
                                rablkcnt =  map[i+1].br_blockcount;
                                rablkno = map[i+1].br_startblock;
                                while (rablkcnt--) {
                                        xfs_buf_readahead(mp->m_ddev_targp,
                                               XFS_FSB_TO_DADDR(mp, rablkno),
                                               mp->m_quotainfo->qi_dqchunklen,
                                               &xfs_dquot_buf_ops);
                                        rablkno++;
                                }
                        }
                        /*
                         * Iterate thru all the blks in the extent and
                         * reset the counters of all the dquots inside them.
                         */
                        error = xfs_qm_dqiter_bufs(mp, firstid,
                                                   map[i].br_startblock,
                                                   map[i].br_blockcount,
                                                   flags, buffer_list);
                        if (error)
                                goto out;
                }
        } while (nmaps > 0);

out:
        kmem_free(map);
        return error;
}

/*
 * Called by dqusage_adjust in doing a quotacheck.
 *
 * Given the inode, and a dquot id this updates both the incore dqout as well
 * as the buffer copy. This is so that once the quotacheck is done, we can
 * just log all the buffers, as opposed to logging numerous updates to
 * individual dquots.
 */
STATIC int
xfs_qm_quotacheck_dqadjust(
        struct xfs_inode        *ip,
        xfs_dqid_t              id,
        uint                    type,
        xfs_qcnt_t              nblks,
        xfs_qcnt_t              rtblks)
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_dquot        *dqp;
        int                     error;

        error = xfs_qm_dqget(mp, ip, id, type,
                             XFS_QMOPT_DQALLOC | XFS_QMOPT_DOWARN, &dqp);
        if (error) {
                /*
                 * Shouldn't be able to turn off quotas here.
                 */
                ASSERT(error != -ESRCH);
                ASSERT(error != -ENOENT);
                return error;
        }

        trace_xfs_dqadjust(dqp);

        /*
         * Adjust the inode count and the block count to reflect this inode's
         * resource usage.
         */
        be64_add_cpu(&dqp->q_core.d_icount, 1);
        dqp->q_res_icount++;
        if (nblks) {
                be64_add_cpu(&dqp->q_core.d_bcount, nblks);
                dqp->q_res_bcount += nblks;
        }
        if (rtblks) {
                be64_add_cpu(&dqp->q_core.d_rtbcount, rtblks);
                dqp->q_res_rtbcount += rtblks;
        }

        /*
         * Set default limits, adjust timers (since we changed usages)
         *
         * There are no timers for the default values set in the root dquot.
         */
        if (dqp->q_core.d_id) {
                xfs_qm_adjust_dqlimits(mp, dqp);
                xfs_qm_adjust_dqtimers(mp, &dqp->q_core);
        }

        dqp->dq_flags |= XFS_DQ_DIRTY;
        xfs_qm_dqput(dqp);
        return 0;
}

STATIC int
xfs_qm_get_rtblks(
        xfs_inode_t     *ip,
        xfs_qcnt_t      *O_rtblks)
{
        xfs_filblks_t   rtblks;                 /* total rt blks */
        xfs_extnum_t    idx;                    /* extent record index */
        xfs_ifork_t     *ifp;                   /* inode fork pointer */
        xfs_extnum_t    nextents;               /* number of extent entries */
        int             error;

        ASSERT(XFS_IS_REALTIME_INODE(ip));
        ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
        if (!(ifp->if_flags & XFS_IFEXTENTS)) {
                if ((error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK)))
                        return error;
        }
        rtblks = 0;
        nextents = ifp->if_bytes / (uint)sizeof(xfs_bmbt_rec_t);
        for (idx = 0; idx < nextents; idx++)
                rtblks += xfs_bmbt_get_blockcount(xfs_iext_get_ext(ifp, idx));
        *O_rtblks = (xfs_qcnt_t)rtblks;
        return 0;
}

/*
 * callback routine supplied to bulkstat(). Given an inumber, find its
 * dquots and update them to account for resources taken by that inode.
 */
/* ARGSUSED */
STATIC int
xfs_qm_dqusage_adjust(
        xfs_mount_t     *mp,            /* mount point for filesystem */
        xfs_ino_t       ino,            /* inode number to get data for */
        void            __user *buffer, /* not used */
        int             ubsize,         /* not used */
        int             *ubused,        /* not used */
        int             *res)           /* result code value */
{
        xfs_inode_t     *ip;
        xfs_qcnt_t      nblks, rtblks = 0;
        int             error;

        ASSERT(XFS_IS_QUOTA_RUNNING(mp));

        /*
         * rootino must have its resources accounted for, not so with the quota
         * inodes.
         */
        if (xfs_is_quota_inode(&mp->m_sb, ino)) {
                *res = BULKSTAT_RV_NOTHING;
                return -EINVAL;
        }

        /*
         * We don't _need_ to take the ilock EXCL. However, the xfs_qm_dqget
         * interface expects the inode to be exclusively locked because that's
         * the case in all other instances. It's OK that we do this because
         * quotacheck is done only at mount time.
         */
        error = xfs_iget(mp, NULL, ino, 0, XFS_ILOCK_EXCL, &ip);
        if (error) {
                *res = BULKSTAT_RV_NOTHING;
                return error;
        }

        ASSERT(ip->i_delayed_blks == 0);

        if (XFS_IS_REALTIME_INODE(ip)) {
                /*
                 * Walk thru the extent list and count the realtime blocks.
                 */
                error = xfs_qm_get_rtblks(ip, &rtblks);
                if (error)
                        goto error0;
        }

        nblks = (xfs_qcnt_t)ip->i_d.di_nblocks - rtblks;

        /*
         * Add the (disk blocks and inode) resources occupied by this
         * inode to its dquots. We do this adjustment in the incore dquot,
         * and also copy the changes to its buffer.
         * We don't care about putting these changes in a transaction
         * envelope because if we crash in the middle of a 'quotacheck'
         * we have to start from the beginning anyway.
         * Once we're done, we'll log all the dquot bufs.
         *
         * The *QUOTA_ON checks below may look pretty racy, but quotachecks
         * and quotaoffs don't race. (Quotachecks happen at mount time only).
         */
        if (XFS_IS_UQUOTA_ON(mp)) {
                error = xfs_qm_quotacheck_dqadjust(ip, ip->i_d.di_uid,
                                                   XFS_DQ_USER, nblks, rtblks);
                if (error)
                        goto error0;
        }

        if (XFS_IS_GQUOTA_ON(mp)) {
                error = xfs_qm_quotacheck_dqadjust(ip, ip->i_d.di_gid,
                                                   XFS_DQ_GROUP, nblks, rtblks);
                if (error)
                        goto error0;
        }

        if (XFS_IS_PQUOTA_ON(mp)) {
                error = xfs_qm_quotacheck_dqadjust(ip, xfs_get_projid(ip),
                                                   XFS_DQ_PROJ, nblks, rtblks);
                if (error)
                        goto error0;
        }

        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        IRELE(ip);
        *res = BULKSTAT_RV_DIDONE;
        return 0;

error0:
        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        IRELE(ip);
        *res = BULKSTAT_RV_GIVEUP;
        return error;
}

STATIC int
xfs_qm_flush_one(
        struct xfs_dquot        *dqp,
        void                    *data)
{
        struct list_head        *buffer_list = data;
        struct xfs_buf          *bp = NULL;
        int                     error = 0;

        xfs_dqlock(dqp);
        if (dqp->dq_flags & XFS_DQ_FREEING)
                goto out_unlock;
        if (!XFS_DQ_IS_DIRTY(dqp))
                goto out_unlock;

        xfs_dqflock(dqp);
        error = xfs_qm_dqflush(dqp, &bp);
        if (error)
                goto out_unlock;

        xfs_buf_delwri_queue(bp, buffer_list);
        xfs_buf_relse(bp);
out_unlock:
        xfs_dqunlock(dqp);
        return error;
}

/*
 * Walk thru all the filesystem inodes and construct a consistent view
 * of the disk quota world. If the quotacheck fails, disable quotas.
 */
STATIC int
xfs_qm_quotacheck(
        xfs_mount_t     *mp)
{
        int                     done, count, error, error2;
        xfs_ino_t               lastino;
        size_t                  structsz;
        uint                    flags;
        LIST_HEAD               (buffer_list);
        struct xfs_inode        *uip = mp->m_quotainfo->qi_uquotaip;
        struct xfs_inode        *gip = mp->m_quotainfo->qi_gquotaip;
        struct xfs_inode        *pip = mp->m_quotainfo->qi_pquotaip;

        count = INT_MAX;
        structsz = 1;
        lastino = 0;
        flags = 0;

        ASSERT(uip || gip || pip);
        ASSERT(XFS_IS_QUOTA_RUNNING(mp));

        xfs_notice(mp, "Quotacheck needed: Please wait.");

        /*
         * First we go thru all the dquots on disk, USR and GRP/PRJ, and reset
         * their counters to zero. We need a clean slate.
         * We don't log our changes till later.
         */
        if (uip) {
                error = xfs_qm_dqiterate(mp, uip, XFS_QMOPT_UQUOTA,
                                         &buffer_list);
                if (error)
                        goto error_return;
                flags |= XFS_UQUOTA_CHKD;
        }

        if (gip) {
                error = xfs_qm_dqiterate(mp, gip, XFS_QMOPT_GQUOTA,
                                         &buffer_list);
                if (error)
                        goto error_return;
                flags |= XFS_GQUOTA_CHKD;
        }

        if (pip) {
                error = xfs_qm_dqiterate(mp, pip, XFS_QMOPT_PQUOTA,
                                         &buffer_list);
                if (error)
                        goto error_return;
                flags |= XFS_PQUOTA_CHKD;
        }

        do {
                /*
                 * Iterate thru all the inodes in the file system,
                 * adjusting the corresponding dquot counters in core.
                 */
                error = xfs_bulkstat(mp, &lastino, &count,
                                     xfs_qm_dqusage_adjust,
                                     structsz, NULL, &done);
                if (error)
                        break;

        } while (!done);

        /*
         * We've made all the changes that we need to make incore.  Flush them
         * down to disk buffers if everything was updated successfully.
         */
        if (XFS_IS_UQUOTA_ON(mp)) {
                error = xfs_qm_dquot_walk(mp, XFS_DQ_USER, xfs_qm_flush_one,
                                          &buffer_list);
        }
        if (XFS_IS_GQUOTA_ON(mp)) {
                error2 = xfs_qm_dquot_walk(mp, XFS_DQ_GROUP, xfs_qm_flush_one,
                                           &buffer_list);
                if (!error)
                        error = error2;
        }
        if (XFS_IS_PQUOTA_ON(mp)) {
                error2 = xfs_qm_dquot_walk(mp, XFS_DQ_PROJ, xfs_qm_flush_one,
                                           &buffer_list);
                if (!error)
                        error = error2;
        }

        error2 = xfs_buf_delwri_submit(&buffer_list);
        if (!error)
                error = error2;

        /*
         * We can get this error if we couldn't do a dquot allocation inside
         * xfs_qm_dqusage_adjust (via bulkstat). We don't care about the
         * dirty dquots that might be cached, we just want to get rid of them
         * and turn quotaoff. The dquots won't be attached to any of the inodes
         * at this point (because we intentionally didn't in dqget_noattach).
         */
        if (error) {
                xfs_qm_dqpurge_all(mp, XFS_QMOPT_QUOTALL);
                goto error_return;
        }

        /*
         * If one type of quotas is off, then it will lose its
         * quotachecked status, since we won't be doing accounting for
         * that type anymore.
         */
        mp->m_qflags &= ~XFS_ALL_QUOTA_CHKD;
        mp->m_qflags |= flags;

 error_return:
        while (!list_empty(&buffer_list)) {
                struct xfs_buf *bp =
                        list_first_entry(&buffer_list, struct xfs_buf, b_list);
                list_del_init(&bp->b_list);
                xfs_buf_relse(bp);
        }

        if (error) {
                xfs_warn(mp,
        "Quotacheck: Unsuccessful (Error %d): Disabling quotas.",
                        error);
                /*
                 * We must turn off quotas.
                 */
                ASSERT(mp->m_quotainfo != NULL);
                xfs_qm_destroy_quotainfo(mp);
                if (xfs_mount_reset_sbqflags(mp)) {
                        xfs_warn(mp,
                                "Quotacheck: Failed to reset quota flags.");
                }
        } else
                xfs_notice(mp, "Quotacheck: Done.");
        return error;
}

/*
 * This is called from xfs_mountfs to start quotas and initialize all
 * necessary data structures like quotainfo.  This is also responsible for
 * running a quotacheck as necessary.  We are guaranteed that the superblock
 * is consistently read in at this point.
 *
 * If we fail here, the mount will continue with quota turned off. We don't
 * need to inidicate success or failure at all.
 */
void
xfs_qm_mount_quotas(
        struct xfs_mount        *mp)
{
        int                     error = 0;
        uint                    sbf;

        /*
         * If quotas on realtime volumes is not supported, we disable
         * quotas immediately.
         */
        if (mp->m_sb.sb_rextents) {
                xfs_notice(mp, "Cannot turn on quotas for realtime filesystem");
                mp->m_qflags = 0;
                goto write_changes;
        }

        ASSERT(XFS_IS_QUOTA_RUNNING(mp));

        /*
         * Allocate the quotainfo structure inside the mount struct, and
         * create quotainode(s), and change/rev superblock if necessary.
         */
        error = xfs_qm_init_quotainfo(mp);
        if (error) {
                /*
                 * We must turn off quotas.
                 */
                ASSERT(mp->m_quotainfo == NULL);
                mp->m_qflags = 0;
                goto write_changes;
        }
        /*
         * If any of the quotas are not consistent, do a quotacheck.
         */
        if (XFS_QM_NEED_QUOTACHECK(mp)) {
                error = xfs_qm_quotacheck(mp);
                if (error) {
                        /* Quotacheck failed and disabled quotas. */
                        return;
                }
        }
        /*
         * If one type of quotas is off, then it will lose its
         * quotachecked status, since we won't be doing accounting for
         * that type anymore.
         */
        if (!XFS_IS_UQUOTA_ON(mp))
                mp->m_qflags &= ~XFS_UQUOTA_CHKD;
        if (!XFS_IS_GQUOTA_ON(mp))
                mp->m_qflags &= ~XFS_GQUOTA_CHKD;
        if (!XFS_IS_PQUOTA_ON(mp))
                mp->m_qflags &= ~XFS_PQUOTA_CHKD;

 write_changes:
        /*
         * We actually don't have to acquire the m_sb_lock at all.
         * This can only be called from mount, and that's single threaded. XXX
         */
        spin_lock(&mp->m_sb_lock);
        sbf = mp->m_sb.sb_qflags;
        mp->m_sb.sb_qflags = mp->m_qflags & XFS_MOUNT_QUOTA_ALL;
        spin_unlock(&mp->m_sb_lock);

        if (sbf != (mp->m_qflags & XFS_MOUNT_QUOTA_ALL)) {
                if (xfs_sync_sb(mp, false)) {
                        /*
                         * We could only have been turning quotas off.
                         * We aren't in very good shape actually because
                         * the incore structures are convinced that quotas are
                         * off, but the on disk superblock doesn't know that !
                         */
                        ASSERT(!(XFS_IS_QUOTA_RUNNING(mp)));
                        xfs_alert(mp, "%s: Superblock update failed!",
                                __func__);
                }
        }

        if (error) {
                xfs_warn(mp, "Failed to initialize disk quotas.");
                return;
        }
}

/*
 * This is called after the superblock has been read in and we're ready to
 * iget the quota inodes.
 */
STATIC int
xfs_qm_init_quotainos(
        xfs_mount_t     *mp)
{
        struct xfs_inode        *uip = NULL;
        struct xfs_inode        *gip = NULL;
        struct xfs_inode        *pip = NULL;
        int                     error;
        uint                    flags = 0;

        ASSERT(mp->m_quotainfo);

        /*
         * Get the uquota and gquota inodes
         */
        if (xfs_sb_version_hasquota(&mp->m_sb)) {
                if (XFS_IS_UQUOTA_ON(mp) &&
                    mp->m_sb.sb_uquotino != NULLFSINO) {
                        ASSERT(mp->m_sb.sb_uquotino > 0);
                        error = xfs_iget(mp, NULL, mp->m_sb.sb_uquotino,
                                             0, 0, &uip);
                        if (error)
                                return error;
                }
                if (XFS_IS_GQUOTA_ON(mp) &&
                    mp->m_sb.sb_gquotino != NULLFSINO) {
                        ASSERT(mp->m_sb.sb_gquotino > 0);
                        error = xfs_iget(mp, NULL, mp->m_sb.sb_gquotino,
                                             0, 0, &gip);
                        if (error)
                                goto error_rele;
                }
                if (XFS_IS_PQUOTA_ON(mp) &&
                    mp->m_sb.sb_pquotino != NULLFSINO) {
                        ASSERT(mp->m_sb.sb_pquotino > 0);
                        error = xfs_iget(mp, NULL, mp->m_sb.sb_pquotino,
                                             0, 0, &pip);
                        if (error)
                                goto error_rele;
                }
        } else {
                flags |= XFS_QMOPT_SBVERSION;
        }

        /*
         * Create the three inodes, if they don't exist already. The changes
         * made above will get added to a transaction and logged in one of
         * the qino_alloc calls below.  If the device is readonly,
         * temporarily switch to read-write to do this.
         */
        if (XFS_IS_UQUOTA_ON(mp) && uip == NULL) {
                error = xfs_qm_qino_alloc(mp, &uip,
                                              flags | XFS_QMOPT_UQUOTA);
                if (error)
                        goto error_rele;

                flags &= ~XFS_QMOPT_SBVERSION;
        }
        if (XFS_IS_GQUOTA_ON(mp) && gip == NULL) {
                error = xfs_qm_qino_alloc(mp, &gip,
                                          flags | XFS_QMOPT_GQUOTA);
                if (error)
                        goto error_rele;

                flags &= ~XFS_QMOPT_SBVERSION;
        }
        if (XFS_IS_PQUOTA_ON(mp) && pip == NULL) {
                error = xfs_qm_qino_alloc(mp, &pip,
                                          flags | XFS_QMOPT_PQUOTA);
                if (error)
                        goto error_rele;
        }

        mp->m_quotainfo->qi_uquotaip = uip;
        mp->m_quotainfo->qi_gquotaip = gip;
        mp->m_quotainfo->qi_pquotaip = pip;

        return 0;

error_rele:
        if (uip)
                IRELE(uip);
        if (gip)
                IRELE(gip);
        if (pip)
                IRELE(pip);
        return error;
}

STATIC void
xfs_qm_dqfree_one(
        struct xfs_dquot        *dqp)
{
        struct xfs_mount        *mp = dqp->q_mount;
        struct xfs_quotainfo    *qi = mp->m_quotainfo;

        mutex_lock(&qi->qi_tree_lock);
        radix_tree_delete(xfs_dquot_tree(qi, dqp->q_core.d_flags),
                          be32_to_cpu(dqp->q_core.d_id));

        qi->qi_dquots--;
        mutex_unlock(&qi->qi_tree_lock);

        xfs_qm_dqdestroy(dqp);
}

/* --------------- utility functions for vnodeops ---------------- */


/*
 * Given an inode, a uid, gid and prid make sure that we have
 * allocated relevant dquot(s) on disk, and that we won't exceed inode
 * quotas by creating this file.
 * This also attaches dquot(s) to the given inode after locking it,
 * and returns the dquots corresponding to the uid and/or gid.
 *
 * in   : inode (unlocked)
 * out  : udquot, gdquot with references taken and unlocked
 */
int
xfs_qm_vop_dqalloc(
        struct xfs_inode        *ip,
        xfs_dqid_t              uid,
        xfs_dqid_t              gid,
        prid_t                  prid,
        uint                    flags,
        struct xfs_dquot        **O_udqpp,
        struct xfs_dquot        **O_gdqpp,
        struct xfs_dquot        **O_pdqpp)
{
        struct xfs_mount        *mp = ip->i_mount;
        struct xfs_dquot        *uq = NULL;
        struct xfs_dquot        *gq = NULL;
        struct xfs_dquot        *pq = NULL;
        int                     error;
        uint                    lockflags;

        if (!XFS_IS_QUOTA_RUNNING(mp) || !XFS_IS_QUOTA_ON(mp))
                return 0;

        lockflags = XFS_ILOCK_EXCL;
        xfs_ilock(ip, lockflags);

        if ((flags & XFS_QMOPT_INHERIT) && XFS_INHERIT_GID(ip))
                gid = ip->i_d.di_gid;

        /*
         * Attach the dquot(s) to this inode, doing a dquot allocation
         * if necessary. The dquot(s) will not be locked.
         */
        if (XFS_NOT_DQATTACHED(mp, ip)) {
                error = xfs_qm_dqattach_locked(ip, XFS_QMOPT_DQALLOC);
                if (error) {
                        xfs_iunlock(ip, lockflags);
                        return error;
                }
        }

        if ((flags & XFS_QMOPT_UQUOTA) && XFS_IS_UQUOTA_ON(mp)) {
                if (ip->i_d.di_uid != uid) {
                        /*
                         * What we need is the dquot that has this uid, and
                         * if we send the inode to dqget, the uid of the inode
                         * takes priority over what's sent in the uid argument.
                         * We must unlock inode here before calling dqget if
                         * we're not sending the inode, because otherwise
                         * we'll deadlock by doing trans_reserve while
                         * holding ilock.
                         */
                        xfs_iunlock(ip, lockflags);
                        error = xfs_qm_dqget(mp, NULL, uid,
                                                 XFS_DQ_USER,
                                                 XFS_QMOPT_DQALLOC |
                                                 XFS_QMOPT_DOWARN,
                                                 &uq);
                        if (error) {
                                ASSERT(error != -ENOENT);
                                return error;
                        }
                        /*
                         * Get the ilock in the right order.
                         */
                        xfs_dqunlock(uq);
                        lockflags = XFS_ILOCK_SHARED;
                        xfs_ilock(ip, lockflags);
                } else {
                        /*
                         * Take an extra reference, because we'll return
                         * this to caller
                         */
                        ASSERT(ip->i_udquot);
                        uq = xfs_qm_dqhold(ip->i_udquot);
                }
        }
        if ((flags & XFS_QMOPT_GQUOTA) && XFS_IS_GQUOTA_ON(mp)) {
                if (ip->i_d.di_gid != gid) {
                        xfs_iunlock(ip, lockflags);
                        error = xfs_qm_dqget(mp, NULL, gid,
                                                 XFS_DQ_GROUP,
                                                 XFS_QMOPT_DQALLOC |
                                                 XFS_QMOPT_DOWARN,
                                                 &gq);
                        if (error) {
                                ASSERT(error != -ENOENT);
                                goto error_rele;
                        }
                        xfs_dqunlock(gq);
                        lockflags = XFS_ILOCK_SHARED;
                        xfs_ilock(ip, lockflags);
                } else {
                        ASSERT(ip->i_gdquot);
                        gq = xfs_qm_dqhold(ip->i_gdquot);
                }
        }
        if ((flags & XFS_QMOPT_PQUOTA) && XFS_IS_PQUOTA_ON(mp)) {
                if (xfs_get_projid(ip) != prid) {
                        xfs_iunlock(ip, lockflags);
                        error = xfs_qm_dqget(mp, NULL, (xfs_dqid_t)prid,
                                                 XFS_DQ_PROJ,
                                                 XFS_QMOPT_DQALLOC |
                                                 XFS_QMOPT_DOWARN,
                                                 &pq);
                        if (error) {
                                ASSERT(error != -ENOENT);
                                goto error_rele;
                        }
                        xfs_dqunlock(pq);
                        lockflags = XFS_ILOCK_SHARED;
                        xfs_ilock(ip, lockflags);
                } else {
                        ASSERT(ip->i_pdquot);
                        pq = xfs_qm_dqhold(ip->i_pdquot);
                }
        }
        if (uq)
                trace_xfs_dquot_dqalloc(ip);

        xfs_iunlock(ip, lockflags);
        if (O_udqpp)
                *O_udqpp = uq;
        else
                xfs_qm_dqrele(uq);
        if (O_gdqpp)
                *O_gdqpp = gq;
        else
                xfs_qm_dqrele(gq);
        if (O_pdqpp)
                *O_pdqpp = pq;
        else
                xfs_qm_dqrele(pq);
        return 0;

error_rele:
        xfs_qm_dqrele(gq);
        xfs_qm_dqrele(uq);
        return error;
}

/*
 * Actually transfer ownership, and do dquot modifications.
 * These were already reserved.
 */
xfs_dquot_t *
xfs_qm_vop_chown(
        xfs_trans_t     *tp,
        xfs_inode_t     *ip,
        xfs_dquot_t     **IO_olddq,
        xfs_dquot_t     *newdq)
{
        xfs_dquot_t     *prevdq;
        uint            bfield = XFS_IS_REALTIME_INODE(ip) ?
                                 XFS_TRANS_DQ_RTBCOUNT : XFS_TRANS_DQ_BCOUNT;


        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
        ASSERT(XFS_IS_QUOTA_RUNNING(ip->i_mount));

        /* old dquot */
        prevdq = *IO_olddq;
        ASSERT(prevdq);
        ASSERT(prevdq != newdq);

        xfs_trans_mod_dquot(tp, prevdq, bfield, -(ip->i_d.di_nblocks));
        xfs_trans_mod_dquot(tp, prevdq, XFS_TRANS_DQ_ICOUNT, -1);

        /* the sparkling new dquot */
        xfs_trans_mod_dquot(tp, newdq, bfield, ip->i_d.di_nblocks);
        xfs_trans_mod_dquot(tp, newdq, XFS_TRANS_DQ_ICOUNT, 1);

        /*
         * Take an extra reference, because the inode is going to keep
         * this dquot pointer even after the trans_commit.
         */
        *IO_olddq = xfs_qm_dqhold(newdq);

        return prevdq;
}

/*
 * Quota reservations for setattr(AT_UID|AT_GID|AT_PROJID).
 */
int
xfs_qm_vop_chown_reserve(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        struct xfs_dquot        *udqp,
        struct xfs_dquot        *gdqp,
        struct xfs_dquot        *pdqp,
        uint                    flags)
{
        struct xfs_mount        *mp = ip->i_mount;
        uint                    delblks, blkflags, prjflags = 0;
        struct xfs_dquot        *udq_unres = NULL;
        struct xfs_dquot        *gdq_unres = NULL;
        struct xfs_dquot        *pdq_unres = NULL;
        struct xfs_dquot        *udq_delblks = NULL;
        struct xfs_dquot        *gdq_delblks = NULL;
        struct xfs_dquot        *pdq_delblks = NULL;
        int                     error;


        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL|XFS_ILOCK_SHARED));
        ASSERT(XFS_IS_QUOTA_RUNNING(mp));

        delblks = ip->i_delayed_blks;
        blkflags = XFS_IS_REALTIME_INODE(ip) ?
                        XFS_QMOPT_RES_RTBLKS : XFS_QMOPT_RES_REGBLKS;

        if (XFS_IS_UQUOTA_ON(mp) && udqp &&
            ip->i_d.di_uid != be32_to_cpu(udqp->q_core.d_id)) {
                udq_delblks = udqp;
                /*
                 * If there are delayed allocation blocks, then we have to
                 * unreserve those from the old dquot, and add them to the
                 * new dquot.
                 */
                if (delblks) {
                        ASSERT(ip->i_udquot);
                        udq_unres = ip->i_udquot;
                }
        }
        if (XFS_IS_GQUOTA_ON(ip->i_mount) && gdqp &&
            ip->i_d.di_gid != be32_to_cpu(gdqp->q_core.d_id)) {
                gdq_delblks = gdqp;
                if (delblks) {
                        ASSERT(ip->i_gdquot);
                        gdq_unres = ip->i_gdquot;
                }
        }

        if (XFS_IS_PQUOTA_ON(ip->i_mount) && pdqp &&
            xfs_get_projid(ip) != be32_to_cpu(pdqp->q_core.d_id)) {
                prjflags = XFS_QMOPT_ENOSPC;
                pdq_delblks = pdqp;
                if (delblks) {
                        ASSERT(ip->i_pdquot);
                        pdq_unres = ip->i_pdquot;
                }
        }

        error = xfs_trans_reserve_quota_bydquots(tp, ip->i_mount,
                                udq_delblks, gdq_delblks, pdq_delblks,
                                ip->i_d.di_nblocks, 1,
                                flags | blkflags | prjflags);
        if (error)
                return error;

        /*
         * Do the delayed blks reservations/unreservations now. Since, these
         * are done without the help of a transaction, if a reservation fails
         * its previous reservations won't be automatically undone by trans
         * code. So, we have to do it manually here.
         */
        if (delblks) {
                /*
                 * Do the reservations first. Unreservation can't fail.
                 */
                ASSERT(udq_delblks || gdq_delblks || pdq_delblks);
                ASSERT(udq_unres || gdq_unres || pdq_unres);
                error = xfs_trans_reserve_quota_bydquots(NULL, ip->i_mount,
                            udq_delblks, gdq_delblks, pdq_delblks,
                            (xfs_qcnt_t)delblks, 0,
                            flags | blkflags | prjflags);
                if (error)
                        return error;
                xfs_trans_reserve_quota_bydquots(NULL, ip->i_mount,
                                udq_unres, gdq_unres, pdq_unres,
                                -((xfs_qcnt_t)delblks), 0, blkflags);
        }

        return 0;
}

int
xfs_qm_vop_rename_dqattach(
        struct xfs_inode        **i_tab)
{
        struct xfs_mount        *mp = i_tab[0]->i_mount;
        int                     i;

        if (!XFS_IS_QUOTA_RUNNING(mp) || !XFS_IS_QUOTA_ON(mp))
                return 0;

        for (i = 0; (i < 4 && i_tab[i]); i++) {
                struct xfs_inode        *ip = i_tab[i];
                int                     error;

                /*
                 * Watch out for duplicate entries in the table.
                 */
                if (i == 0 || ip != i_tab[i-1]) {
                        if (XFS_NOT_DQATTACHED(mp, ip)) {
                                error = xfs_qm_dqattach(ip, 0);
                                if (error)
                                        return error;
                        }
                }
        }
        return 0;
}

void
xfs_qm_vop_create_dqattach(
        struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        struct xfs_dquot        *udqp,
        struct xfs_dquot        *gdqp,
        struct xfs_dquot        *pdqp)
{
        struct xfs_mount        *mp = tp->t_mountp;

        if (!XFS_IS_QUOTA_RUNNING(mp) || !XFS_IS_QUOTA_ON(mp))
                return;

        ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
        ASSERT(XFS_IS_QUOTA_RUNNING(mp));

        if (udqp && XFS_IS_UQUOTA_ON(mp)) {
                ASSERT(ip->i_udquot == NULL);
                ASSERT(ip->i_d.di_uid == be32_to_cpu(udqp->q_core.d_id));

                ip->i_udquot = xfs_qm_dqhold(udqp);
                xfs_trans_mod_dquot(tp, udqp, XFS_TRANS_DQ_ICOUNT, 1);
        }
        if (gdqp && XFS_IS_GQUOTA_ON(mp)) {
                ASSERT(ip->i_gdquot == NULL);
                ASSERT(ip->i_d.di_gid == be32_to_cpu(gdqp->q_core.d_id));
                ip->i_gdquot = xfs_qm_dqhold(gdqp);
                xfs_trans_mod_dquot(tp, gdqp, XFS_TRANS_DQ_ICOUNT, 1);
        }
        if (pdqp && XFS_IS_PQUOTA_ON(mp)) {
                ASSERT(ip->i_pdquot == NULL);
                ASSERT(xfs_get_projid(ip) == be32_to_cpu(pdqp->q_core.d_id));

                ip->i_pdquot = xfs_qm_dqhold(pdqp);
                xfs_trans_mod_dquot(tp, pdqp, XFS_TRANS_DQ_ICOUNT, 1);
        }
}