/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will 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 version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2012, 2017, Intel Corporation.
 * Use is subject to license terms.
 *
 * Author: Johann Lombardi <johann.lombardi@intel.com>
 * Author: Niu    Yawei    <yawei.niu@intel.com>
 */

#define DEBUG_SUBSYSTEM S_LQUOTA

#include <obd_class.h>
#include "qmt_internal.h"

/*
 * Retrieve quota settings for a given identifier.
 *
 * \param env     - is the environment passed by the caller
 * \param qmt     - is the quota master target
 * \param restype - is the pool type, either block (i.e. LQUOTA_RES_DT) or inode
 *                  (i.e. LQUOTA_RES_MD)
 * \param qtype   - is the quota type
 * \param id      - is the quota indentifier for which we want to acces quota
 *                  settings.
 * \param hard    - is the output variable where to copy the hard limit
 * \param soft    - is the output variable where to copy the soft limit
 * \param time    - is the output variable where to copy the grace time
 */
static int qmt_get(const struct lu_env *env, struct qmt_device *qmt,
		   __u8 restype, __u8 qtype, union lquota_id *id,
		   __u64 *hard, __u64 *soft, __u64 *time, bool is_default,
		   char *pool_name)
{
	struct lquota_entry	*lqe;
	ENTRY;

	LASSERT(!is_default || id->qid_uid == 0);
	if (pool_name && !strnlen(pool_name, LOV_MAXPOOLNAME))
		pool_name = NULL;

	/* look-up lqe structure containing quota settings */
	lqe = qmt_pool_lqe_lookup(env, qmt, restype, qtype, id, pool_name);
	if (IS_ERR(lqe))
		RETURN(PTR_ERR(lqe));

	/* copy quota settings */
	lqe_read_lock(lqe);
	LQUOTA_DEBUG(lqe, "fetch settings");
	if (hard != NULL)
		*hard = lqe->lqe_hardlimit;
	if (soft != NULL)
		*soft = lqe->lqe_softlimit;
	if (time != NULL) {
		*time = lqe->lqe_gracetime;
		if (lqe->lqe_is_default)
			*time |= (__u64)LQUOTA_FLAG_DEFAULT <<
							LQUOTA_GRACE_BITS;
	}
	lqe_read_unlock(lqe);

	lqe_putref(lqe);
	RETURN(0);
}

struct qmt_entry_iter_data {
	const struct lu_env *qeid_env;
	struct qmt_device   *qeid_qmt;
};

static int qmt_entry_iter_cb(struct cfs_hash *hs, struct cfs_hash_bd *bd,
			     struct hlist_node *hnode, void *d)
{
	struct qmt_entry_iter_data *iter = (struct qmt_entry_iter_data *)d;
	struct lquota_entry	*lqe;

	lqe = hlist_entry(hnode, struct lquota_entry, lqe_hash);
	LASSERT(atomic_read(&lqe->lqe_ref) > 0);

	if (lqe->lqe_id.qid_uid == 0 || !lqe->lqe_is_default)
		return 0;

	return qmt_set_with_lqe(iter->qeid_env, iter->qeid_qmt, lqe, 0, 0, 0, 0,
				true, true);
}

static void qmt_set_id_notify(const struct lu_env *env, struct qmt_device *qmt,
			      struct lquota_entry *lqe)
{
	struct lquota_entry *lqe_gl;
	int rc;

	lqe_gl = lqe->lqe_is_global ? lqe : NULL;
	rc = qmt_pool_lqes_lookup_spec(env, qmt, lqe_rtype(lqe),
				       lqe_qtype(lqe), &lqe->lqe_id);
	if (!qti_lqes_cnt(env))
		GOTO(lqes_fini, rc);

	if (!lqe_gl && qti_lqes_glbl(env)->lqe_is_global)
		lqe_gl = qti_lqes_glbl(env);

	if (!lqe_gl)
		GOTO(lqes_fini, rc);

	if (lqe_gl->lqe_glbl_data)
		qmt_seed_glbe(env, lqe_gl->lqe_glbl_data);
	/* Even if slaves haven't enqueued quota lock yet,
	 * it is needed to set lqe_revoke_time in qmt_id_lock_glimpse
	 * in case of reaching qpi_least_qunit */
	qmt_id_lock_notify(qmt, lqe_gl);
lqes_fini:
	qti_lqes_fini(env);
}

/*
 * Update quota settings for a given lqe.
 *
 * \param env        - is the environment passed by the caller
 * \param qmt        - is the quota master target
 * \param lqe        - is the lquota_entry for which we want to modify quota
 *                     settings.
 * \param hard       - is the new hard limit
 * \param soft       - is the new soft limit
 * \param time       - is the new grace time
 * \param valid      - is the list of settings to change
 * \param is_default - true for default quota setting
 * \param is_updated - true if the lqe is updated and no need to write back
 */

int qmt_set_with_lqe(const struct lu_env *env, struct qmt_device *qmt,
		     struct lquota_entry *lqe, __u64 hard, __u64 soft,
		     __u64 time, __u32 valid, bool is_default, bool is_updated)
{
	struct thandle *th = NULL;
	time64_t now = 0;
	__u64 ver;
	bool dirtied = false;
	int rc = 0;
	bool need_id_notify = false;
	ENTRY;

	/* need to write back to global quota file? */
	if (!is_updated) {
		/* By default we should have here only 1 lqe,
		 * so no allocations should be done. */
		if (qti_lqes_restore_init(env))
			GOTO(out_nolock, rc = -ENOMEM);
		/* allocate & start transaction with enough credits to update
		 * quota  settings in the global index file */
		th = qmt_trans_start(env, lqe);
		if (IS_ERR(th))
			GOTO(out_nolock, rc = PTR_ERR(th));
	}

	now = ktime_get_real_seconds();

	lqe_write_lock(lqe);
	LQUOTA_DEBUG(lqe,
		     "changing quota settings valid:%x hard:%llu soft:%llu time:%llu",
		     valid, hard, soft, time);

	if (is_default && lqe->lqe_id.qid_uid != 0) {
		LQUOTA_DEBUG(lqe, "set qid %llu to use default quota setting",
			     lqe->lqe_id.qid_uid);

		qmt_lqe_set_default(env, lqe->lqe_site->lqs_parent, lqe, false);
		GOTO(quota_set, 0);
	}

	if ((valid & QIF_TIMES) != 0 && lqe->lqe_gracetime != time) {
		/* change time settings */
		lqe->lqe_gracetime = time;
		dirtied            = true;
	}

	if ((valid & QIF_LIMITS) != 0 &&
	    (lqe->lqe_hardlimit != hard || lqe->lqe_softlimit != soft)) {
		rc = qmt_validate_limits(lqe, hard, soft);
		if (rc)
			GOTO(out, rc);

		/* change quota limits */
		lqe->lqe_hardlimit = hard;
		lqe->lqe_softlimit = soft;

quota_set:
		/* recompute qunit in case it was never initialized */
		if (qmt_revalidate(env, lqe))
			need_id_notify = true;

		/* clear grace time */
		if (lqe->lqe_softlimit == 0 ||
		    lqe->lqe_granted <= lqe->lqe_softlimit)
			/* no soft limit or below soft limit, let's clear grace
			 * time */
			lqe->lqe_gracetime = 0;
		else if ((valid & QIF_TIMES) == 0)
			/* set grace only if user hasn't provided his own */
			 lqe->lqe_gracetime = now + qmt_lqe_grace(lqe);

		/* change enforced status based on new parameters */
		if (lqe->lqe_id.qid_uid == 0 || (lqe->lqe_hardlimit == 0 &&
		    lqe->lqe_softlimit == 0))
			lqe->lqe_enforced = false;
		else
			lqe->lqe_enforced = true;

		dirtied = true;
	}

	if (!is_default && lqe->lqe_is_default) {
		LQUOTA_DEBUG(lqe, "the qid %llu has been set quota"
			     " explicitly, clear the default flag",
			     lqe->lqe_id.qid_uid);

		qmt_lqe_clear_default(lqe);
		dirtied = true;
	}

	if (dirtied) {
		if (!is_updated) {
			/* write new quota settings to disk */
			rc = qmt_glb_write(env, th, lqe, LQUOTA_BUMP_VER, &ver);
			if (rc) {
				/* restore initial quota settings */
				qmt_restore(lqe, &qti_lqes_rstr(env)[0]);
				GOTO(out, rc);
			}
		} else {
			ver = dt_version_get(env, LQE_GLB_OBJ(lqe));
		}

		/* compute new qunit value now that we have modified the quota
		 * settings or clear/set edquot flag if needed */
		need_id_notify |= qmt_adjust_qunit(env, lqe);
		need_id_notify |= qmt_adjust_edquot(lqe, now);
	}
	EXIT;
out:
	lqe_write_unlock(lqe);

out_nolock:
	if (!is_updated) {
		if (th != NULL && !IS_ERR(th))
			dt_trans_stop(env, qmt->qmt_child, th);
		qti_lqes_restore_fini(env);
	}

	if (rc == 0 && dirtied) {
		qmt_glb_lock_notify(env, lqe, ver);
		if (lqe->lqe_id.qid_uid == 0) {
			struct qmt_entry_iter_data iter_data;

			LQUOTA_DEBUG(lqe, "notify all lqe with default quota");
			iter_data.qeid_env = env;
			iter_data.qeid_qmt = qmt;
			cfs_hash_for_each(lqe->lqe_site->lqs_hash,
					       qmt_entry_iter_cb, &iter_data);
			/* Always notify slaves with default values. Don't
			 * care about overhead as will be sent only not changed
			 * values(see qmt_id_lock_cb for details).*/
			need_id_notify = true;
		}
		/* qti_lqes_inited > 0 means we came here from another
		 * qmt_pool_lqes_lookup(qmt_dqacq, intent_policy ...). Thus
		 * we can't init and add new lqes to don't overwrite already
		 * added.
		 */
		if (!qti_lqes_inited(env) && need_id_notify)
			qmt_set_id_notify(env, qmt, lqe);
	}

	return rc;
}

/*
 * Update quota settings for a given identifier.
 *
 * \param env        - is the environment passed by the caller
 * \param qmt        - is the quota master target
 * \param restype    - is the pool type, either block (i.e. LQUOTA_RES_DT) or
 *                     inode (i.e. LQUOTA_RES_MD)
 * \param qtype      - is the quota type
 * \param id         - is the quota indentifier for which we want to modify
 *                     quota settings.
 * \param hard       - is the new hard limit
 * \param soft       - is the new soft limit
 * \param time       - is the new grace time
 * \param valid      - is the list of settings to change
 * \param is_default - true for default quota setting
 * \param is_updated - true if the lqe is updated and no need to write back
 */
static int qmt_set(const struct lu_env *env, struct qmt_device *qmt,
		   __u8 restype, __u8 qtype, union lquota_id *id,
		   __u64 hard, __u64 soft, __u64 time, __u32 valid,
		   bool is_default, bool is_updated, char *pool_name)
{
	struct lquota_entry *lqe;
	int rc;
	ENTRY;

	if (pool_name && !strnlen(pool_name, LOV_MAXPOOLNAME))
		pool_name = NULL;

	/* look-up quota entry associated with this ID */
	lqe = qmt_pool_lqe_lookup(env, qmt, restype, qtype, id, pool_name);
	if (IS_ERR(lqe))
			RETURN(PTR_ERR(lqe));

	rc = qmt_set_with_lqe(env, qmt, lqe, hard, soft, time, valid,
			      is_default, is_updated);
	lqe_putref(lqe);
	RETURN(rc);
}

/*
 * Handle quotactl request.
 *
 * \param env   - is the environment passed by the caller
 * \param ld    - is the lu device associated with the qmt
 * \param oqctl - is the quotactl request
 */
static int qmt_quotactl(const struct lu_env *env, struct lu_device *ld,
			struct obd_quotactl *oqctl)
{
	struct qmt_thread_info *qti = qmt_info(env);
	union lquota_id	*id  = &qti->qti_id;
	struct qmt_device *qmt = lu2qmt_dev(ld);
	struct obd_dqblk *dqb = &oqctl->qc_dqblk;
	char *poolname;
	int rc = 0;
	bool is_default = false;
	ENTRY;

	LASSERT(qmt != NULL);

	if (oqctl->qc_type >= LL_MAXQUOTAS)
		/* invalid quota type */
		RETURN(-EINVAL);

	poolname = LUSTRE_Q_CMD_IS_POOL(oqctl->qc_cmd) ?
			oqctl->qc_poolname : NULL;

	switch (oqctl->qc_cmd) {

	case Q_GETINFO:  /* read grace times */
	case LUSTRE_Q_GETINFOPOOL:
		/* Global grace time is stored in quota settings of ID 0. */
		id->qid_uid = 0;

		/* read inode grace time */
		rc = qmt_get(env, qmt, LQUOTA_RES_MD, oqctl->qc_type, id, NULL,
			     NULL, &oqctl->qc_dqinfo.dqi_igrace,
			     false, poolname);
		/* There could be no MD pool, so try to find DT pool */
		if (rc && rc != -ENOENT)
			break;

		/* read block grace time */
		rc = qmt_get(env, qmt, LQUOTA_RES_DT, oqctl->qc_type, id, NULL,
			     NULL, &oqctl->qc_dqinfo.dqi_bgrace,
			     false, poolname);
		break;

	case Q_SETINFO:  /* modify grace times */
	case LUSTRE_Q_SETINFOPOOL:
		/* setinfo should be using dqi->dqi_valid, but lfs incorrectly
		 * sets the valid flags in dqb->dqb_valid instead, try to live
		 * with that ... */

		/* Global grace time is stored in quota settings of ID 0. */
		id->qid_uid = 0;

		if ((dqb->dqb_valid & QIF_ITIME) != 0) {
			/* set inode grace time */
			rc = qmt_set(env, qmt, LQUOTA_RES_MD, oqctl->qc_type,
				     id, 0, 0, oqctl->qc_dqinfo.dqi_igrace,
				     QIF_TIMES, false, false,
				     poolname);
			if (rc)
				break;
		}

		if ((dqb->dqb_valid & QIF_BTIME) != 0)
			/* set block grace time */
			rc = qmt_set(env, qmt, LQUOTA_RES_DT, oqctl->qc_type,
				     id, 0, 0, oqctl->qc_dqinfo.dqi_bgrace,
				     QIF_TIMES, false, false,
				     poolname);
		break;

	case LUSTRE_Q_GETDEFAULT:
	case LUSTRE_Q_GETDEFAULT_POOL:
		is_default = true;
		/* fallthrough */

	case Q_GETQUOTA: /* consult quota limit */
	case LUSTRE_Q_GETQUOTAPOOL:
		/* extract quota ID from quotactl request */
		id->qid_uid = oqctl->qc_id;

		/* look-up inode quota settings */
		rc = qmt_get(env, qmt, LQUOTA_RES_MD, oqctl->qc_type, id,
			     &dqb->dqb_ihardlimit, &dqb->dqb_isoftlimit,
			     &dqb->dqb_itime, is_default, poolname);
		/* There could be no MD pool, so try to find DT pool */
		if (rc && rc != -ENOENT)
			break;
		else
			dqb->dqb_valid |= QIF_ILIMITS | QIF_ITIME;

		/* master isn't aware of actual inode usage */
		dqb->dqb_curinodes = 0;

		/* look-up block quota settings */
		rc = qmt_get(env, qmt, LQUOTA_RES_DT, oqctl->qc_type, id,
			     &dqb->dqb_bhardlimit, &dqb->dqb_bsoftlimit,
			     &dqb->dqb_btime, is_default, poolname);
		if (rc)
			break;

		dqb->dqb_valid |= QIF_BLIMITS | QIF_BTIME;
		/* master doesn't know the actual block usage */
		dqb->dqb_curspace = 0;
		break;

	case LUSTRE_Q_SETDEFAULT:
	case LUSTRE_Q_SETDEFAULT_POOL:
		is_default = true;
		/* fallthrough */

	case Q_SETQUOTA: /* change quota limits */
	case LUSTRE_Q_SETQUOTAPOOL:
		/* extract quota ID from quotactl request */
		id->qid_uid = oqctl->qc_id;

		if ((dqb->dqb_valid & QIF_IFLAGS) != 0) {
			/* update inode quota settings */
			rc = qmt_set(env, qmt, LQUOTA_RES_MD, oqctl->qc_type,
				     id, dqb->dqb_ihardlimit,
				     dqb->dqb_isoftlimit, dqb->dqb_itime,
				     dqb->dqb_valid & QIF_IFLAGS, is_default,
				     false, poolname);
			if (rc)
				break;
		}

		if ((dqb->dqb_valid & QIF_BFLAGS) != 0)
			/* update block quota settings */
			rc = qmt_set(env, qmt, LQUOTA_RES_DT, oqctl->qc_type,
				     id, dqb->dqb_bhardlimit,
				     dqb->dqb_bsoftlimit, dqb->dqb_btime,
				     dqb->dqb_valid & QIF_BFLAGS, is_default,
				     false, poolname);
		break;

	default:
		CERROR("%s: unsupported quotactl command: %d\n",
		       qmt->qmt_svname, oqctl->qc_cmd);
		RETURN(-ENOTSUPP);
	}

	RETURN(rc);
}

static inline
void qmt_grant_lqes(const struct lu_env *env, __u64 *slv, __u64 cnt)
{
	int i;

	for (i = 0; i < qti_lqes_cnt(env); i++)
		qti_lqe_granted(env, i) += cnt;

	*slv += cnt;
}

static inline bool qmt_lqes_can_rel(const struct lu_env *env, __u64 cnt)
{
	bool can_release = true;
	int i;

	for (i = 0; i < qti_lqes_cnt(env); i++) {
		if (cnt > qti_lqe_granted(env, i)) {
			LQUOTA_ERROR(qti_lqes(env)[i],
				     "Can't release %llu that is larger than lqe_granted.\n",
				     cnt);
			can_release = false;
		}
	}
	return can_release;
}

static inline void qmt_rel_lqes(const struct lu_env *env, __u64 *slv, __u64 cnt)
{
	int i;

	for (i = 0; i < qti_lqes_cnt(env); i++)
		qti_lqe_granted(env, i) -= cnt;

	*slv -= cnt;
}

static inline bool qmt_lqes_cannot_grant(const struct lu_env *env, __u64 cnt)
{
	bool cannot_grant = false;
	int i;

	for (i = 0; i < qti_lqes_cnt(env); i++) {
		if (qti_lqe_hard(env, i) != 0 &&
		    qti_lqe_granted(env, i) + cnt > qti_lqe_hard(env, i)) {
			cannot_grant = true;
			break;
		}
	}
	return cannot_grant;
}

static inline __u64 qmt_lqes_grant_some_quota(const struct lu_env *env)
{
	__u64 min_count, tmp;
	bool flag = false;
	int i;

	for (i = 0, min_count = 0; i < qti_lqes_cnt(env); i++) {
		if (!qti_lqes(env)[i]->lqe_enforced &&
		    !qti_lqes(env)[i]->lqe_is_global)
			continue;

		tmp = qti_lqe_hard(env, i) - qti_lqe_granted(env, i);
		if (flag) {
			min_count = tmp < min_count ? tmp : min_count;
		} else {
			flag = true;
			min_count = tmp;
		}
	}
	return min_count;
}

static inline __u64 qmt_lqes_alloc_expand(const struct lu_env *env,
					  __u64 slv_granted, __u64 spare)
{
	__u64 min_count, tmp;
	bool flag = false;
	int i;

	for (i = 0, min_count = 0; i < qti_lqes_cnt(env); i++) {
		/* Don't take into account not enforced lqes that belong
		 * to non global pool. These lqes present in array to
		 * support actual lqe_granted even for lqes without limits. */
		if (!qti_lqes(env)[i]->lqe_enforced &&
		    !qti_lqes(env)[i]->lqe_is_global)
			continue;

		tmp = qmt_alloc_expand(qti_lqes(env)[i], slv_granted, spare);
		if (flag) {
			min_count = tmp < min_count ? tmp : min_count;
		} else {
			flag = true;
			min_count = tmp;
		}
	}
	return min_count;
}

static inline void qmt_lqes_tune_grace(const struct lu_env *env, __u64 now)
{
	int i;

	for (i = 0; i < qti_lqes_cnt(env); i++) {
		struct lquota_entry *lqe;

		lqe = qti_lqes(env)[i];
		if (lqe->lqe_softlimit != 0) {
			if (lqe->lqe_granted > lqe->lqe_softlimit &&
			    lqe->lqe_gracetime == 0) {
				/* First time over soft limit, let's start grace
				 * timer */
				lqe->lqe_gracetime = now + qmt_lqe_grace(lqe);
			} else if (lqe->lqe_granted <= lqe->lqe_softlimit &&
				   lqe->lqe_gracetime != 0) {
				/* Clear grace timer */
				lqe->lqe_gracetime = 0;
			}
		}
	}
}

/*
 * Helper function to handle quota request from slave.
 *
 * \param env     - is the environment passed by the caller
 * \param qmt     - is the master device
 * \param uuid    - is the uuid associated with the slave
 * \param qb_flags - are the quota request flags as packed in the quota_body
 * \param qb_count - is the amount of quota space the slave wants to
 *                   acquire/release
 * \param qb_usage - is the current space usage on the slave
 * \param repbody - is the quota_body of reply
 *
 * \retval 0            : success
 * \retval -EDQUOT      : out of quota
 *         -EINPROGRESS : inform client to retry write/create
 *         -ve          : other appropriate errors
 */
int qmt_dqacq0(const struct lu_env *env, struct qmt_device *qmt,
	       struct obd_uuid *uuid, __u32 qb_flags, __u64 qb_count,
	       __u64 qb_usage, struct quota_body *repbody)
{
	__u64			 now, count;
	struct dt_object	*slv_obj = NULL;
	__u64			 slv_granted, slv_granted_bck;
	struct thandle		*th = NULL;
	int			 rc, ret;
	struct lquota_entry *lqe = qti_lqes_glbl(env);
	ENTRY;

	LASSERT(uuid != NULL);

	/* initialize reply */
	memset(repbody, 0, sizeof(*repbody));
	memcpy(&repbody->qb_id, &lqe->lqe_id, sizeof(repbody->qb_id));

	if (OBD_FAIL_CHECK(OBD_FAIL_QUOTA_RECOVERABLE_ERR))
		RETURN(-cfs_fail_val);

	if (qti_lqes_restore_init(env))
		RETURN(-ENOMEM);

	/* look-up index file associated with acquiring slave */
	slv_obj = lquota_disk_slv_find(env, qmt->qmt_child, LQE_ROOT(lqe),
				       lu_object_fid(&LQE_GLB_OBJ(lqe)->do_lu),
				       uuid);
	if (IS_ERR(slv_obj))
		GOTO(out, rc = PTR_ERR(slv_obj));

	/* pack slave fid in reply just for sanity check */
	memcpy(&repbody->qb_slv_fid, lu_object_fid(&slv_obj->do_lu),
	       sizeof(struct lu_fid));

	/* allocate & start transaction with enough credits to update
	 * global & slave indexes */
	th = qmt_trans_start_with_slv(env, NULL, slv_obj, false);
	if (IS_ERR(th))
		GOTO(out, rc = PTR_ERR(th));

	qti_lqes_write_lock(env);

	LQUOTA_DEBUG_LQES(env, "dqacq starts uuid:%s flags:0x%x wanted:%llu"
		     " usage:%llu", obd_uuid2str(uuid), qb_flags, qb_count,
		     qb_usage);

	/* Legal race, limits have been removed on master, but slave didn't
	 * receive the change yet. Just return EINPROGRESS until the slave gets
	 * notified. */
	if (!lqe->lqe_enforced && !req_is_rel(qb_flags))
		GOTO(out_locked, rc = -ESRCH);

	/* recompute qunit in case it was never initialized */
	qmt_revalidate_lqes(env, qmt, qb_flags);

	/* slave just wants to acquire per-ID lock */
	if (req_is_acq(qb_flags) && qb_count == 0)
		GOTO(out_locked, rc = 0);

	/* fetch how much quota space is already granted to this slave */
	rc = qmt_slv_read(env, &lqe->lqe_id, slv_obj, &slv_granted);
	if (rc) {
		LQUOTA_ERROR(lqe, "Failed to get granted for slave %s, rc=%d",
			     obd_uuid2str(uuid), rc);
		GOTO(out_locked, rc);
	}
	/* recall how much space this slave currently owns in order to restore
	 * it in case of failure */
	slv_granted_bck = slv_granted;

	/* record current time for soft limit & grace time management */
	now = ktime_get_real_seconds();

	if (req_is_rel(qb_flags)) {
		/* Slave would like to release quota space */
		if (slv_granted < qb_count ||
		    !qmt_lqes_can_rel(env, qb_count)) {
			/* can't release more than granted */
			LQUOTA_ERROR_LQES(env,
					  "Release too much! uuid:%s release: %llu granted:%llu, total:%llu",
					  obd_uuid2str(uuid), qb_count,
					  slv_granted, lqe->lqe_granted);
			GOTO(out_locked, rc = -EINVAL);
		}

		repbody->qb_count = qb_count;
		/* put released space back to global pool */
		qmt_rel_lqes(env, &slv_granted, qb_count);
		GOTO(out_write, rc = 0);
	}

	if (req_has_rep(qb_flags) && slv_granted < qb_usage) {
		/* Slave is reporting space usage in quota request and it turns
		 * out to be using more quota space than owned, so we adjust
		 * granted space regardless of the current state of affairs */
		repbody->qb_count = qb_usage - slv_granted;
		qmt_grant_lqes(env, &slv_granted, repbody->qb_count);
	}

	if (!req_is_acq(qb_flags) && !req_is_preacq(qb_flags))
		GOTO(out_write, rc = 0);

	qmt_adjust_edquot_notify(env, qmt, now, qb_flags);
	if (qti_lqes_edquot(env))
		/* no hope to claim further space back */
		GOTO(out_write, rc = -EDQUOT);

	if (qmt_space_exhausted_lqes(env, now)) {
		/* might have some free space once rebalancing is completed */
		rc = req_is_acq(qb_flags) ? -EINPROGRESS : -EDQUOT;
		GOTO(out_write, rc);
	}

	if (req_is_preacq(qb_flags)) {
		/* slave would like to pre-acquire quota space. To do so, it
		 * reports in qb_count how much spare quota space it owns and we
		 * can grant back quota space which is consistent with qunit
		 * value. */
		if (qb_count >= qti_lqes_min_qunit(env))
			/* slave already own the maximum it should */
			GOTO(out_write, rc = 0);

		count = qmt_lqes_alloc_expand(env, slv_granted, qb_count);
		if (count == 0)
			GOTO(out_write, rc = -EDQUOT);

		repbody->qb_count += count;
		qmt_grant_lqes(env, &slv_granted, count);
		GOTO(out_write, rc = 0);
	}

	/* processing acquire request with clients waiting */
	if (qmt_lqes_cannot_grant(env, qb_count)) {
		/* cannot grant as much as asked, but can still afford to grant
		 * some quota space back */
		count = qmt_lqes_grant_some_quota(env);
		repbody->qb_count += count;
		qmt_grant_lqes(env, &slv_granted, count);
		GOTO(out_write, rc = 0);
	}

	/* Whouhou! we can satisfy the slave request! */
	repbody->qb_count += qb_count;
	qmt_grant_lqes(env, &slv_granted, qb_count);

	/* Try to expand the acquired count for DQACQ */
	count = qmt_lqes_alloc_expand(env, slv_granted, 0);
	if (count != 0) {
		/* can even grant more than asked, it is like xmas ... */
		repbody->qb_count += count;
		qmt_grant_lqes(env, &slv_granted, count);
		GOTO(out_write, rc = 0);
	}

	GOTO(out_write, rc = 0);
out_write:
	if (repbody->qb_count == 0)
		GOTO(out_locked, rc);

	/* start/stop grace timer if required */
	qmt_lqes_tune_grace(env, now);

	/* Update slave index first since it is easier to roll back */
	ret = qmt_slv_write(env, th, lqe, slv_obj, LQUOTA_BUMP_VER,
			    &repbody->qb_slv_ver, slv_granted);
	if (ret) {
		/* restore initial quota settings */
		qmt_restore_lqes(env);
		/* reset qb_count */
		repbody->qb_count = 0;
		GOTO(out_locked, rc = ret);
	}

	/* Update global index, no version bump needed */
	ret = qmt_glb_write_lqes(env, th, 0, NULL);
	if (ret) {
		rc = ret;
		/* restore initial quota settings */
		qmt_restore_lqes(env);
		/* reset qb_count */
		repbody->qb_count = 0;

		/* restore previous granted value */
		ret = qmt_slv_write(env, th, lqe, slv_obj, 0, NULL,
				    slv_granted_bck);
		if (ret) {
			LQUOTA_ERROR(lqe, "failed to restore initial slave "
				     "value rc:%d ret%d", rc, ret);
			LBUG();
		}
		qmt_adjust_edquot_notify(env, qmt, now, qb_flags);
		GOTO(out_locked, rc);
	}

	/* Total granted has been changed, let's try to adjust the qunit
	 * size according to the total granted & limits. */

	/* clear/set edquot flag and notify slaves via glimpse if needed */
	qmt_adjust_and_notify(env, qmt, now, qb_flags);
out_locked:
	LQUOTA_DEBUG_LQES(env, "dqacq ends count:%llu ver:%llu rc:%d",
		     repbody->qb_count, repbody->qb_slv_ver, rc);
	qti_lqes_write_unlock(env);
out:
	qti_lqes_restore_fini(env);

	if (th != NULL && !IS_ERR(th))
		dt_trans_stop(env, qmt->qmt_child, th);

	if (slv_obj != NULL && !IS_ERR(slv_obj))
		dt_object_put(env, slv_obj);

	if ((req_is_acq(qb_flags) || req_is_preacq(qb_flags)) &&
	    OBD_FAIL_CHECK(OBD_FAIL_QUOTA_EDQUOT)) {
		/* introduce inconsistency between granted value in slave index
		 * and slave index copy of slave */
		repbody->qb_count = 0;
		rc = -EDQUOT;
	}

	RETURN(rc);
}

/*
 * Extract index from uuid or quota index file name.
 *
 * \param[in] uuid	uuid or quota index name(0x1020000-OST0001_UUID)
 * \param[out] idx	pointer to save index
 *
 * \retval		slave type(QMT_STYPE_MDT or QMT_STYPE_OST)
 * \retval -EINVAL	wrong uuid
 */
int qmt_uuid2idx(struct obd_uuid *uuid, int *idx)
{
	char *uuid_str, *name, *dash;
	int rc = -EINVAL;

	uuid_str = (char *)uuid->uuid;

	if (strnlen(uuid_str, UUID_MAX) >= UUID_MAX) {
		CERROR("quota: UUID '%.*s' missing trailing NUL: rc = %d\n",
		       UUID_MAX, uuid_str, rc);
		return rc;
	}

	dash = strrchr(uuid_str, '-');
	name = dash + 1;
	/* Going to get index from MDTXXXX/OSTXXXX. Thus uuid should
	 * have at least 8 bytes after '-': 3 for MDT/OST, 4 for index
	 * and 1 byte for null character. */
	if (*dash != '-' || ((uuid_str + UUID_MAX - name) < 8)) {
		CERROR("quota: wrong UUID format '%s': rc = %d\n",
		       uuid_str, rc);
		return rc;
	}

	rc = target_name2index(name, idx, NULL);
	switch (rc) {
	case LDD_F_SV_TYPE_MDT:
		rc = QMT_STYPE_MDT;
		break;
	case LDD_F_SV_TYPE_OST:
		rc = QMT_STYPE_OST;
		break;
	default:
		CERROR("quota: wrong UUID type '%s': rc = %d\n", uuid_str, rc);
		rc = -EINVAL;
	}

	RETURN(rc);
}

/*
 * Handle quota request from slave.
 *
 * \param env  - is the environment passed by the caller
 * \param ld   - is the lu device associated with the qmt
 * \param req  - is the quota acquire request
 */
static int qmt_dqacq(const struct lu_env *env, struct lu_device *ld,
		     struct ptlrpc_request *req)
{
	struct qmt_device *qmt = lu2qmt_dev(ld);
	struct quota_body *qbody, *repbody;
	struct obd_uuid	*uuid;
	struct ldlm_lock *lock;
	int rtype, qtype;
	int rc, idx, stype;
	ENTRY;

	qbody = req_capsule_client_get(&req->rq_pill, &RMF_QUOTA_BODY);
	if (qbody == NULL)
		RETURN(err_serious(-EPROTO));

	repbody = req_capsule_server_get(&req->rq_pill, &RMF_QUOTA_BODY);
	if (repbody == NULL)
		RETURN(err_serious(-EFAULT));

	/* verify if global lock is stale */
	if (!lustre_handle_is_used(&qbody->qb_glb_lockh))
		RETURN(-ENOLCK);

	lock = ldlm_handle2lock(&qbody->qb_glb_lockh);
	if (lock == NULL)
		RETURN(-ENOLCK);
	LDLM_LOCK_PUT(lock);

	uuid = &req->rq_export->exp_client_uuid;
	stype = qmt_uuid2idx(uuid, &idx);
	if (stype < 0)
		RETURN(stype);

	if (req_is_rel(qbody->qb_flags) + req_is_acq(qbody->qb_flags) +
	    req_is_preacq(qbody->qb_flags) > 1) {
		CERROR("%s: malformed quota request with conflicting flags set "
		       "(%x) from slave %s\n", qmt->qmt_svname,
		       qbody->qb_flags, obd_uuid2str(uuid));
		RETURN(-EPROTO);
	}

	if (req_is_acq(qbody->qb_flags) || req_is_preacq(qbody->qb_flags)) {
		/* acquire and pre-acquire should use a valid ID lock */

		if (!lustre_handle_is_used(&qbody->qb_lockh))
			RETURN(-ENOLCK);

		lock = ldlm_handle2lock(&qbody->qb_lockh);
		if (lock == NULL)
			/* no lock associated with this handle */
			RETURN(-ENOLCK);

		LDLM_DEBUG(lock, "%sacquire request",
			   req_is_preacq(qbody->qb_flags) ? "pre" : "");

		if (!obd_uuid_equals(&lock->l_export->exp_client_uuid, uuid)) {
			/* sorry, no way to cheat ... */
			LDLM_LOCK_PUT(lock);
			RETURN(-ENOLCK);
		}

		if (ldlm_is_ast_sent(lock)) {
			struct ptlrpc_service_part *svc;
			timeout_t timeout;

			svc = req->rq_rqbd->rqbd_svcpt;
			timeout = at_est2timeout(at_get(&svc->scp_at_estimate));
			timeout += (ldlm_bl_timeout(lock) >> 1);

			/* lock is being cancelled, prolong timeout */
			ldlm_refresh_waiting_lock(lock, timeout);
		}
		LDLM_LOCK_PUT(lock);
	}

	/* extract quota information from global index FID packed in the
	 * request */
	rc = lquota_extract_fid(&qbody->qb_fid, &rtype, &qtype);
	if (rc)
		RETURN(-EINVAL);

	/* Find the quota entry associated with the quota id */
	rc = qmt_pool_lqes_lookup(env, qmt, rtype, stype, qtype,
				  &qbody->qb_id, NULL, idx);
	if (rc)
		RETURN(rc);

	rc = qmt_dqacq0(env, qmt, uuid, qbody->qb_flags,
			qbody->qb_count, qbody->qb_usage, repbody);

	if (lustre_handle_is_used(&qbody->qb_lockh))
		/* return current qunit value only to slaves owning an per-ID
		 * quota lock. For enqueue, the qunit value will be returned in
		 * the LVB */
		repbody->qb_qunit = qti_lqes_min_qunit(env);
	CDEBUG(D_QUOTA, "qmt_dqacq return qb_qunit %llu qb_count %llu\n",
	       repbody->qb_qunit, repbody->qb_count);
	qti_lqes_fini(env);
	RETURN(rc);
}

/* Vector of quota request handlers. This vector is used by the MDT to forward
 * requests to the quota master. */
struct qmt_handlers qmt_hdls = {
	/* quota request handlers */
	.qmth_quotactl		= qmt_quotactl,
	.qmth_dqacq		= qmt_dqacq,

	/* ldlm handlers */
	.qmth_intent_policy	= qmt_intent_policy,
	.qmth_lvbo_init		= qmt_lvbo_init,
	.qmth_lvbo_update	= qmt_lvbo_update,
	.qmth_lvbo_size		= qmt_lvbo_size,
	.qmth_lvbo_fill		= qmt_lvbo_fill,
	.qmth_lvbo_free		= qmt_lvbo_free,
};
EXPORT_SYMBOL(qmt_hdls);