// SPDX-License-Identifier: GPL-2.0

  /*

   * Copyright (c) 2000-2003 Silicon Graphics, Inc.
   * All Rights Reserved.

   */

  #include "xfs.h"
  #include "xfs_fs.h"

  #include "xfs_format.h"

  #include "xfs_log_format.h"

  #include "xfs_shared.h"

  #include "xfs_trans_resv.h"

  #include "xfs_bit.h"

  #include "xfs_mount.h"

  #include "xfs_defer.h"

  #include "xfs_inode.h"
  #include "xfs_bmap.h"

  #include "xfs_quota.h"

  #include "xfs_trans.h"

  #include "xfs_buf_item.h"
  #include "xfs_trans_space.h"
  #include "xfs_trans_priv.h"

  #include "xfs_qm.h"

  #include "xfs_trace.h"

  #include "xfs_log.h"

  #include "xfs_bmap_btree.h"

  #include "xfs_error.h"

  /*

   * Lock order:
   *
   * ip->i_lock

   *   qi->qi_tree_lock

   *     dquot->q_qlock (xfs_dqlock() and friends)
   *       dquot->q_flush (xfs_dqflock() and friends)
   *       qi->qi_lru_lock

   *
   * If two dquots need to be locked the order is user before group/project,
   * otherwise by the lowest id first, see xfs_dqlock2.
   */

  struct kmem_zone		*xfs_qm_dqtrxzone;
  static struct kmem_zone		*xfs_qm_dqzone;

  static struct lock_class_key xfs_dquot_group_class;
  static struct lock_class_key xfs_dquot_project_class;

  /*

   * This is called to free all the memory associated with a dquot
   */
  void
  xfs_qm_dqdestroy(

  	struct xfs_dquot	*dqp)

  {

  	ASSERT(list_empty(&dqp->q_lru));

  	kmem_free(dqp->q_logitem.qli_item.li_lv_shadow);

  	mutex_destroy(&dqp->q_qlock);

  	XFS_STATS_DEC(dqp->q_mount, xs_qm_dquot);

  	kmem_cache_free(xfs_qm_dqzone, dqp);

  }
  
  /*

   * If default limits are in force, push them into the dquot now.
   * We overwrite the dquot limits only if they are zero and this
   * is not the root dquot.
   */
  void
  xfs_qm_adjust_dqlimits(

  	struct xfs_dquot	*dq)

  {

  	struct xfs_mount	*mp = dq->q_mount;

  	struct xfs_quotainfo	*q = mp->m_quotainfo;

  	struct xfs_def_quota	*defq;

  	int			prealloc = 0;

  	ASSERT(dq->q_id);

  	defq = xfs_get_defquota(q, xfs_dquot_type(dq));

  	if (!dq->q_blk.softlimit) {

  		dq->q_blk.softlimit = defq->blk.soft;

  		prealloc = 1;
  	}

  	if (!dq->q_blk.hardlimit) {

  		dq->q_blk.hardlimit = defq->blk.hard;

  		prealloc = 1;
  	}

  	if (!dq->q_ino.softlimit)

  		dq->q_ino.softlimit = defq->ino.soft;

  	if (!dq->q_ino.hardlimit)

  		dq->q_ino.hardlimit = defq->ino.hard;

  	if (!dq->q_rtb.softlimit)

  		dq->q_rtb.softlimit = defq->rtb.soft;

  	if (!dq->q_rtb.hardlimit)

  		dq->q_rtb.hardlimit = defq->rtb.hard;

  
  	if (prealloc)
  		xfs_dquot_set_prealloc_limits(dq);

  }

  /* Set the expiration time of a quota's grace period. */
  time64_t
  xfs_dquot_set_timeout(
  	struct xfs_mount	*mp,
  	time64_t		timeout)
  {
  	struct xfs_quotainfo	*qi = mp->m_quotainfo;
  
  	return clamp_t(time64_t, timeout, qi->qi_expiry_min,
  					  qi->qi_expiry_max);
  }

  /* Set the length of the default grace period. */
  time64_t
  xfs_dquot_set_grace_period(
  	time64_t		grace)
  {
  	return clamp_t(time64_t, grace, XFS_DQ_GRACE_MIN, XFS_DQ_GRACE_MAX);
  }

  /*

   * Determine if this quota counter is over either limit and set the quota
   * timers as appropriate.
   */
  static inline void
  xfs_qm_adjust_res_timer(

  	struct xfs_mount	*mp,

  	struct xfs_dquot_res	*res,
  	struct xfs_quota_limits	*qlim)
  {
  	ASSERT(res->hardlimit == 0 || res->softlimit <= res->hardlimit);
  
  	if ((res->softlimit && res->count > res->softlimit) ||
  	    (res->hardlimit && res->count > res->hardlimit)) {
  		if (res->timer == 0)

  			res->timer = xfs_dquot_set_timeout(mp,
  					ktime_get_real_seconds() + qlim->time);

  	} else {
  		if (res->timer == 0)
  			res->warnings = 0;
  		else
  			res->timer = 0;
  	}
  }
  
  /*

   * Check the limits and timers of a dquot and start or reset timers
   * if necessary.
   * This gets called even when quota enforcement is OFF, which makes our
   * life a little less complicated. (We just don't reject any quota
   * reservations in that case, when enforcement is off).
   * We also return 0 as the values of the timers in Q_GETQUOTA calls, when
   * enforcement's off.
   * In contrast, warnings are a little different in that they don't

   * 'automatically' get started when limits get exceeded.  They do
   * get reset to zero, however, when we find the count to be under
   * the soft limit (they are only ever set non-zero via userspace).

   */
  void
  xfs_qm_adjust_dqtimers(

  	struct xfs_dquot	*dq)

  {

  	struct xfs_mount	*mp = dq->q_mount;

  	struct xfs_quotainfo	*qi = mp->m_quotainfo;

  	struct xfs_def_quota	*defq;

  	ASSERT(dq->q_id);

  	defq = xfs_get_defquota(qi, xfs_dquot_type(dq));

  	xfs_qm_adjust_res_timer(dq->q_mount, &dq->q_blk, &defq->blk);
  	xfs_qm_adjust_res_timer(dq->q_mount, &dq->q_ino, &defq->ino);
  	xfs_qm_adjust_res_timer(dq->q_mount, &dq->q_rtb, &defq->rtb);

  }
  
  /*

   * initialize a buffer full of dquots and log the whole thing
   */
  STATIC void
  xfs_qm_init_dquot_blk(

  	struct xfs_trans	*tp,
  	struct xfs_mount	*mp,
  	xfs_dqid_t		id,

  	xfs_dqtype_t		type,

  	struct xfs_buf		*bp)

  {

  	struct xfs_quotainfo	*q = mp->m_quotainfo;

  	struct xfs_dqblk	*d;
  	xfs_dqid_t		curid;
  	unsigned int		qflag;
  	unsigned int		blftype;
  	int			i;

  
  	ASSERT(tp);

  	ASSERT(xfs_buf_islocked(bp));

  	switch (type) {
  	case XFS_DQTYPE_USER:
  		qflag = XFS_UQUOTA_CHKD;
  		blftype = XFS_BLF_UDQUOT_BUF;
  		break;
  	case XFS_DQTYPE_PROJ:
  		qflag = XFS_PQUOTA_CHKD;
  		blftype = XFS_BLF_PDQUOT_BUF;
  		break;
  	case XFS_DQTYPE_GROUP:
  		qflag = XFS_GQUOTA_CHKD;
  		blftype = XFS_BLF_GDQUOT_BUF;
  		break;
  	default:
  		ASSERT(0);
  		return;
  	}

  	d = bp->b_addr;

  
  	/*
  	 * ID of the first dquot in the block - id's are zero based.
  	 */

  	curid = id - (id % q->qi_dqperchunk);

  	memset(d, 0, BBTOB(q->qi_dqchunklen));

  	for (i = 0; i < q->qi_dqperchunk; i++, d++, curid++) {
  		d->dd_diskdq.d_magic = cpu_to_be16(XFS_DQUOT_MAGIC);
  		d->dd_diskdq.d_version = XFS_DQUOT_VERSION;
  		d->dd_diskdq.d_id = cpu_to_be32(curid);

  		d->dd_diskdq.d_type = type;

  		if (curid > 0 && xfs_sb_version_hasbigtime(&mp->m_sb))
  			d->dd_diskdq.d_type |= XFS_DQTYPE_BIGTIME;

  		if (xfs_sb_version_hascrc(&mp->m_sb)) {

  			uuid_copy(&d->dd_uuid, &mp->m_sb.sb_meta_uuid);

  			xfs_update_cksum((char *)d, sizeof(struct xfs_dqblk),
  					 XFS_DQUOT_CRC_OFF);
  		}

  	}

  	xfs_trans_dquot_buf(tp, bp, blftype);
  
  	/*
  	 * quotacheck uses delayed writes to update all the dquots on disk in an
  	 * efficient manner instead of logging the individual dquot changes as
  	 * they are made. However if we log the buffer allocated here and crash
  	 * after quotacheck while the logged initialisation is still in the
  	 * active region of the log, log recovery can replay the dquot buffer
  	 * initialisation over the top of the checked dquots and corrupt quota
  	 * accounting.
  	 *
  	 * To avoid this problem, quotacheck cannot log the initialised buffer.
  	 * We must still dirty the buffer and write it back before the
  	 * allocation transaction clears the log. Therefore, mark the buffer as
  	 * ordered instead of logging it directly. This is safe for quotacheck
  	 * because it detects and repairs allocated but initialized dquot blocks
  	 * in the quota inodes.
  	 */
  	if (!(mp->m_qflags & qflag))
  		xfs_trans_ordered_buf(tp, bp);
  	else
  		xfs_trans_log_buf(tp, bp, 0, BBTOB(q->qi_dqchunklen) - 1);

  }

  /*
   * Initialize the dynamic speculative preallocation thresholds. The lo/hi
   * watermarks correspond to the soft and hard limits by default. If a soft limit
   * is not specified, we use 95% of the hard limit.
   */
  void
  xfs_dquot_set_prealloc_limits(struct xfs_dquot *dqp)
  {

  	uint64_t space;

  	dqp->q_prealloc_hi_wmark = dqp->q_blk.hardlimit;
  	dqp->q_prealloc_lo_wmark = dqp->q_blk.softlimit;

  	if (!dqp->q_prealloc_lo_wmark) {
  		dqp->q_prealloc_lo_wmark = dqp->q_prealloc_hi_wmark;
  		do_div(dqp->q_prealloc_lo_wmark, 100);
  		dqp->q_prealloc_lo_wmark *= 95;
  	}
  
  	space = dqp->q_prealloc_hi_wmark;
  
  	do_div(space, 100);
  	dqp->q_low_space[XFS_QLOWSP_1_PCNT] = space;
  	dqp->q_low_space[XFS_QLOWSP_3_PCNT] = space * 3;
  	dqp->q_low_space[XFS_QLOWSP_5_PCNT] = space * 5;
  }

  /*

   * Ensure that the given in-core dquot has a buffer on disk backing it, and

   * return the buffer locked and held. This is called when the bmapi finds a
   * hole.

   */
  STATIC int

  xfs_dquot_disk_alloc(
  	struct xfs_trans	**tpp,
  	struct xfs_dquot	*dqp,
  	struct xfs_buf		**bpp)

  {

  	struct xfs_bmbt_irec	map;

  	struct xfs_trans	*tp = *tpp;
  	struct xfs_mount	*mp = tp->t_mountp;

  	struct xfs_buf		*bp;

  	xfs_dqtype_t		qtype = xfs_dquot_type(dqp);

  	struct xfs_inode	*quotip = xfs_quota_inode(mp, qtype);

  	int			nmaps = 1;
  	int			error;

  
  	trace_xfs_dqalloc(dqp);

  	xfs_ilock(quotip, XFS_ILOCK_EXCL);

  	if (!xfs_this_quota_on(dqp->q_mount, qtype)) {

  		/*
  		 * Return if this type of quotas is turned off while we didn't
  		 * have an inode lock
  		 */

  		xfs_iunlock(quotip, XFS_ILOCK_EXCL);

  		return -ESRCH;

  	}

  	/* Create the block mapping. */

  	xfs_trans_ijoin(tp, quotip, XFS_ILOCK_EXCL);
  	error = xfs_bmapi_write(tp, quotip, dqp->q_fileoffset,

  			XFS_DQUOT_CLUSTER_SIZE_FSB, XFS_BMAPI_METADATA, 0, &map,
  			&nmaps);

  	if (error)

  		return error;

  	ASSERT(map.br_blockcount == XFS_DQUOT_CLUSTER_SIZE_FSB);
  	ASSERT(nmaps == 1);
  	ASSERT((map.br_startblock != DELAYSTARTBLOCK) &&
  	       (map.br_startblock != HOLESTARTBLOCK));
  
  	/*
  	 * Keep track of the blkno to save a lookup later
  	 */
  	dqp->q_blkno = XFS_FSB_TO_DADDR(mp, map.br_startblock);
  
  	/* now we can just get the buffer (there's nothing to read yet) */

  	error = xfs_trans_get_buf(tp, mp->m_ddev_targp, dqp->q_blkno,
  			mp->m_quotainfo->qi_dqchunklen, 0, &bp);
  	if (error)
  		return error;

  	bp->b_ops = &xfs_dquot_buf_ops;

  	/*
  	 * Make a chunk of dquots out of this buffer and log
  	 * the entire thing.
  	 */

  	xfs_qm_init_dquot_blk(tp, mp, dqp->q_id, qtype, bp);

  	xfs_buf_set_ref(bp, XFS_DQUOT_REF);

  	/*

  	 * Hold the buffer and join it to the dfops so that we'll still own
  	 * the buffer when we return to the caller.  The buffer disposal on
  	 * error must be paid attention to very carefully, as it has been
  	 * broken since commit efa092f3d4c6 "[XFS] Fixes a bug in the quota
  	 * code when allocating a new dquot record" in 2005, and the later
  	 * conversion to xfs_defer_ops in commit 310a75a3c6c747 failed to keep
  	 * the buffer locked across the _defer_finish call.  We can now do
  	 * this correctly with xfs_defer_bjoin.

  	 *

  	 * Above, we allocated a disk block for the dquot information and used
  	 * get_buf to initialize the dquot. If the _defer_finish fails, the old

  	 * transaction is gone but the new buffer is not joined or held to any
  	 * transaction, so we must _buf_relse it.

  	 *

  	 * If everything succeeds, the caller of this function is returned a

  	 * buffer that is locked and held to the transaction.  The caller

  	 * is responsible for unlocking any buffer passed back, either

  	 * manually or by committing the transaction.  On error, the buffer is
  	 * released and not passed back.

  	 */

  	xfs_trans_bhold(tp, bp);

  	error = xfs_defer_finish(tpp);

  	if (error) {

  		xfs_trans_bhold_release(*tpp, bp);
  		xfs_trans_brelse(*tpp, bp);

  		return error;

  	}

  	*bpp = bp;

  	return 0;

  }

  /*

   * Read in the in-core dquot's on-disk metadata and return the buffer.
   * Returns ENOENT to signal a hole.

   */
  STATIC int

  xfs_dquot_disk_read(
  	struct xfs_mount	*mp,
  	struct xfs_dquot	*dqp,
  	struct xfs_buf		**bpp)

  {

  	struct xfs_bmbt_irec	map;

  	struct xfs_buf		*bp;

  	xfs_dqtype_t		qtype = xfs_dquot_type(dqp);

  	struct xfs_inode	*quotip = xfs_quota_inode(mp, qtype);

  	uint			lock_mode;

  	int			nmaps = 1;
  	int			error;

  	lock_mode = xfs_ilock_data_map_shared(quotip);

  	if (!xfs_this_quota_on(mp, qtype)) {

  		/*

  		 * Return if this type of quotas is turned off while we
  		 * didn't have the quota inode lock.

  		 */

  		xfs_iunlock(quotip, lock_mode);

  		return -ESRCH;

  	}
  
  	/*
  	 * Find the block map; no allocations yet
  	 */

  	error = xfs_bmapi_read(quotip, dqp->q_fileoffset,

  			XFS_DQUOT_CLUSTER_SIZE_FSB, &map, &nmaps, 0);

  	xfs_iunlock(quotip, lock_mode);

  	if (error)
  		return error;
  
  	ASSERT(nmaps == 1);

  	ASSERT(map.br_blockcount >= 1);
  	ASSERT(map.br_startblock != DELAYSTARTBLOCK);
  	if (map.br_startblock == HOLESTARTBLOCK)
  		return -ENOENT;
  
  	trace_xfs_dqtobp_read(dqp);

  
  	/*

  	 * store the blkno etc so that we don't have to do the
  	 * mapping all the time

  	 */

  	dqp->q_blkno = XFS_FSB_TO_DADDR(mp, map.br_startblock);

  	error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp, dqp->q_blkno,
  			mp->m_quotainfo->qi_dqchunklen, 0, &bp,
  			&xfs_dquot_buf_ops);
  	if (error) {
  		ASSERT(bp == NULL);
  		return error;

  	}

  	ASSERT(xfs_buf_islocked(bp));

  	xfs_buf_set_ref(bp, XFS_DQUOT_REF);
  	*bpp = bp;

  	return 0;

  }

  /* Allocate and initialize everything we need for an incore dquot. */
  STATIC struct xfs_dquot *
  xfs_dquot_alloc(

  	struct xfs_mount	*mp,
  	xfs_dqid_t		id,

  	xfs_dqtype_t		type)

  {

  	struct xfs_dquot	*dqp;

  	dqp = kmem_cache_zalloc(xfs_qm_dqzone, GFP_KERNEL | __GFP_NOFAIL);

  	dqp->q_type = type;

  	dqp->q_id = id;

  	dqp->q_mount = mp;

  	INIT_LIST_HEAD(&dqp->q_lru);

  	mutex_init(&dqp->q_qlock);
  	init_waitqueue_head(&dqp->q_pinwait);

  	dqp->q_fileoffset = (xfs_fileoff_t)id / mp->m_quotainfo->qi_dqperchunk;
  	/*
  	 * Offset of dquot in the (fixed sized) dquot chunk.
  	 */
  	dqp->q_bufoffset = (id % mp->m_quotainfo->qi_dqperchunk) *
  			sizeof(xfs_dqblk_t);

  
  	/*
  	 * Because we want to use a counting completion, complete
  	 * the flush completion once to allow a single access to
  	 * the flush completion without blocking.
  	 */
  	init_completion(&dqp->q_flush);
  	complete(&dqp->q_flush);
  
  	/*
  	 * Make sure group quotas have a different lock class than user
  	 * quotas.
  	 */

  	switch (type) {

  	case XFS_DQTYPE_USER:

  		/* uses the default lock class */
  		break;

  	case XFS_DQTYPE_GROUP:

  		lockdep_set_class(&dqp->q_qlock, &xfs_dquot_group_class);
  		break;

  	case XFS_DQTYPE_PROJ:

  		lockdep_set_class(&dqp->q_qlock, &xfs_dquot_project_class);
  		break;
  	default:
  		ASSERT(0);
  		break;
  	}

  	xfs_qm_dquot_logitem_init(dqp);

  	XFS_STATS_INC(mp, xs_qm_dquot);

  	return dqp;
  }
  
  /* Copy the in-core quota fields in from the on-disk buffer. */

  STATIC int

  xfs_dquot_from_disk(
  	struct xfs_dquot	*dqp,

  	struct xfs_buf		*bp)

  {

  	struct xfs_disk_dquot	*ddqp = bp->b_addr + dqp->q_bufoffset;

  	/*
  	 * Ensure that we got the type and ID we were looking for.
  	 * Everything else was checked by the dquot buffer verifier.
  	 */

  	if ((ddqp->d_type & XFS_DQTYPE_REC_MASK) != xfs_dquot_type(dqp) ||

  	    be32_to_cpu(ddqp->d_id) != dqp->q_id) {

  		xfs_alert_tag(bp->b_mount, XFS_PTAG_VERIFIER_ERROR,
  			  "Metadata corruption detected at %pS, quota %u",

  			  __this_address, dqp->q_id);

  		xfs_alert(bp->b_mount, "Unmount and run xfs_repair");
  		return -EFSCORRUPTED;
  	}

  	/* copy everything from disk dquot to the incore dquot */

  	dqp->q_type = ddqp->d_type;

  	dqp->q_blk.hardlimit = be64_to_cpu(ddqp->d_blk_hardlimit);
  	dqp->q_blk.softlimit = be64_to_cpu(ddqp->d_blk_softlimit);
  	dqp->q_ino.hardlimit = be64_to_cpu(ddqp->d_ino_hardlimit);
  	dqp->q_ino.softlimit = be64_to_cpu(ddqp->d_ino_softlimit);
  	dqp->q_rtb.hardlimit = be64_to_cpu(ddqp->d_rtb_hardlimit);
  	dqp->q_rtb.softlimit = be64_to_cpu(ddqp->d_rtb_softlimit);

  	dqp->q_blk.count = be64_to_cpu(ddqp->d_bcount);
  	dqp->q_ino.count = be64_to_cpu(ddqp->d_icount);
  	dqp->q_rtb.count = be64_to_cpu(ddqp->d_rtbcount);

  	dqp->q_blk.warnings = be16_to_cpu(ddqp->d_bwarns);
  	dqp->q_ino.warnings = be16_to_cpu(ddqp->d_iwarns);
  	dqp->q_rtb.warnings = be16_to_cpu(ddqp->d_rtbwarns);

  	dqp->q_blk.timer = xfs_dquot_from_disk_ts(ddqp, ddqp->d_btimer);
  	dqp->q_ino.timer = xfs_dquot_from_disk_ts(ddqp, ddqp->d_itimer);
  	dqp->q_rtb.timer = xfs_dquot_from_disk_ts(ddqp, ddqp->d_rtbtimer);

  	/*
  	 * Reservation counters are defined as reservation plus current usage
  	 * to avoid having to add every time.
  	 */

  	dqp->q_blk.reserved = dqp->q_blk.count;
  	dqp->q_ino.reserved = dqp->q_ino.count;
  	dqp->q_rtb.reserved = dqp->q_rtb.count;

  
  	/* initialize the dquot speculative prealloc thresholds */
  	xfs_dquot_set_prealloc_limits(dqp);

  	return 0;

  }

  /* Copy the in-core quota fields into the on-disk buffer. */
  void
  xfs_dquot_to_disk(
  	struct xfs_disk_dquot	*ddqp,
  	struct xfs_dquot	*dqp)
  {

  	ddqp->d_magic = cpu_to_be16(XFS_DQUOT_MAGIC);
  	ddqp->d_version = XFS_DQUOT_VERSION;

  	ddqp->d_type = dqp->q_type;

  	ddqp->d_id = cpu_to_be32(dqp->q_id);
  	ddqp->d_pad0 = 0;
  	ddqp->d_pad = 0;

  	ddqp->d_blk_hardlimit = cpu_to_be64(dqp->q_blk.hardlimit);
  	ddqp->d_blk_softlimit = cpu_to_be64(dqp->q_blk.softlimit);
  	ddqp->d_ino_hardlimit = cpu_to_be64(dqp->q_ino.hardlimit);
  	ddqp->d_ino_softlimit = cpu_to_be64(dqp->q_ino.softlimit);
  	ddqp->d_rtb_hardlimit = cpu_to_be64(dqp->q_rtb.hardlimit);
  	ddqp->d_rtb_softlimit = cpu_to_be64(dqp->q_rtb.softlimit);

  
  	ddqp->d_bcount = cpu_to_be64(dqp->q_blk.count);
  	ddqp->d_icount = cpu_to_be64(dqp->q_ino.count);
  	ddqp->d_rtbcount = cpu_to_be64(dqp->q_rtb.count);

  
  	ddqp->d_bwarns = cpu_to_be16(dqp->q_blk.warnings);
  	ddqp->d_iwarns = cpu_to_be16(dqp->q_ino.warnings);
  	ddqp->d_rtbwarns = cpu_to_be16(dqp->q_rtb.warnings);

  	ddqp->d_btimer = xfs_dquot_to_disk_ts(dqp, dqp->q_blk.timer);
  	ddqp->d_itimer = xfs_dquot_to_disk_ts(dqp, dqp->q_ino.timer);
  	ddqp->d_rtbtimer = xfs_dquot_to_disk_ts(dqp, dqp->q_rtb.timer);

  }

  /* Allocate and initialize the dquot buffer for this in-core dquot. */
  static int
  xfs_qm_dqread_alloc(
  	struct xfs_mount	*mp,
  	struct xfs_dquot	*dqp,
  	struct xfs_buf		**bpp)
  {
  	struct xfs_trans	*tp;

  	int			error;
  
  	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_qm_dqalloc,
  			XFS_QM_DQALLOC_SPACE_RES(mp), 0, 0, &tp);
  	if (error)
  		goto err;

  	error = xfs_dquot_disk_alloc(&tp, dqp, bpp);

  	if (error)
  		goto err_cancel;
  
  	error = xfs_trans_commit(tp);
  	if (error) {
  		/*
  		 * Buffer was held to the transaction, so we have to unlock it
  		 * manually here because we're not passing it back.
  		 */

  		xfs_buf_relse(*bpp);
  		*bpp = NULL;

  		goto err;
  	}

  	return 0;
  
  err_cancel:
  	xfs_trans_cancel(tp);
  err:
  	return error;
  }

  /*
   * Read in the ondisk dquot using dqtobp() then copy it to an incore version,

   * and release the buffer immediately.  If @can_alloc is true, fill any
   * holes in the on-disk metadata.

   */

  static int

  xfs_qm_dqread(
  	struct xfs_mount	*mp,
  	xfs_dqid_t		id,

  	xfs_dqtype_t		type,

  	bool			can_alloc,

  	struct xfs_dquot	**dqpp)

  {
  	struct xfs_dquot	*dqp;

  	struct xfs_buf		*bp;

  	int			error;
  
  	dqp = xfs_dquot_alloc(mp, id, type);

  	trace_xfs_dqread(dqp);

  	/* Try to read the buffer, allocating if necessary. */
  	error = xfs_dquot_disk_read(mp, dqp, &bp);

  	if (error == -ENOENT && can_alloc)

  		error = xfs_qm_dqread_alloc(mp, dqp, &bp);
  	if (error)
  		goto err;

  
  	/*

  	 * At this point we should have a clean locked buffer.  Copy the data
  	 * to the incore dquot and release the buffer since the incore dquot
  	 * has its own locking protocol so we needn't tie up the buffer any
  	 * further.

  	 */

  	ASSERT(xfs_buf_islocked(bp));

  	error = xfs_dquot_from_disk(dqp, bp);

  	xfs_buf_relse(bp);

  	if (error)
  		goto err;

  	*dqpp = dqp;

  	return error;

  err:
  	trace_xfs_dqread_fail(dqp);

  	xfs_qm_dqdestroy(dqp);

  	*dqpp = NULL;

  	return error;

  }
  
  /*

   * Advance to the next id in the current chunk, or if at the
   * end of the chunk, skip ahead to first id in next allocated chunk
   * using the SEEK_DATA interface.
   */

  static int

  xfs_dq_get_next_id(

  	struct xfs_mount	*mp,

  	xfs_dqtype_t		type,

  	xfs_dqid_t		*id)

  {

  	struct xfs_inode	*quotip = xfs_quota_inode(mp, type);
  	xfs_dqid_t		next_id = *id + 1; /* simple advance */
  	uint			lock_flags;
  	struct xfs_bmbt_irec	got;

  	struct xfs_iext_cursor	cur;

  	xfs_fsblock_t		start;

  	int			error = 0;

  	/* If we'd wrap past the max ID, stop */
  	if (next_id < *id)
  		return -ENOENT;

  	/* If new ID is within the current chunk, advancing it sufficed */
  	if (next_id % mp->m_quotainfo->qi_dqperchunk) {
  		*id = next_id;
  		return 0;
  	}
  
  	/* Nope, next_id is now past the current chunk, so find the next one */
  	start = (xfs_fsblock_t)next_id / mp->m_quotainfo->qi_dqperchunk;

  	lock_flags = xfs_ilock_data_map_shared(quotip);
  	if (!(quotip->i_df.if_flags & XFS_IFEXTENTS)) {
  		error = xfs_iread_extents(NULL, quotip, XFS_DATA_FORK);
  		if (error)
  			return error;
  	}

  	if (xfs_iext_lookup_extent(quotip, &quotip->i_df, start, &cur, &got)) {

  		/* contiguous chunk, bump startoff for the id calculation */
  		if (got.br_startoff < start)
  			got.br_startoff = start;

  		*id = got.br_startoff * mp->m_quotainfo->qi_dqperchunk;

  	} else {

  		error = -ENOENT;

  	}

  	xfs_iunlock(quotip, lock_flags);

  	return error;

  }
  
  /*

   * Look up the dquot in the in-core cache.  If found, the dquot is returned
   * locked and ready to go.
   */
  static struct xfs_dquot *
  xfs_qm_dqget_cache_lookup(
  	struct xfs_mount	*mp,
  	struct xfs_quotainfo	*qi,
  	struct radix_tree_root	*tree,
  	xfs_dqid_t		id)
  {
  	struct xfs_dquot	*dqp;
  
  restart:
  	mutex_lock(&qi->qi_tree_lock);
  	dqp = radix_tree_lookup(tree, id);
  	if (!dqp) {
  		mutex_unlock(&qi->qi_tree_lock);
  		XFS_STATS_INC(mp, xs_qm_dqcachemisses);
  		return NULL;
  	}
  
  	xfs_dqlock(dqp);

  	if (dqp->q_flags & XFS_DQFLAG_FREEING) {

  		xfs_dqunlock(dqp);
  		mutex_unlock(&qi->qi_tree_lock);
  		trace_xfs_dqget_freeing(dqp);
  		delay(1);
  		goto restart;
  	}
  
  	dqp->q_nrefs++;
  	mutex_unlock(&qi->qi_tree_lock);
  
  	trace_xfs_dqget_hit(dqp);
  	XFS_STATS_INC(mp, xs_qm_dqcachehits);
  	return dqp;
  }
  
  /*
   * Try to insert a new dquot into the in-core cache.  If an error occurs the
   * caller should throw away the dquot and start over.  Otherwise, the dquot
   * is returned locked (and held by the cache) as if there had been a cache
   * hit.
   */
  static int
  xfs_qm_dqget_cache_insert(
  	struct xfs_mount	*mp,
  	struct xfs_quotainfo	*qi,
  	struct radix_tree_root	*tree,
  	xfs_dqid_t		id,
  	struct xfs_dquot	*dqp)
  {
  	int			error;
  
  	mutex_lock(&qi->qi_tree_lock);
  	error = radix_tree_insert(tree, id, dqp);
  	if (unlikely(error)) {
  		/* Duplicate found!  Caller must try again. */
  		WARN_ON(error != -EEXIST);
  		mutex_unlock(&qi->qi_tree_lock);
  		trace_xfs_dqget_dup(dqp);
  		return error;
  	}
  
  	/* Return a locked dquot to the caller, with a reference taken. */
  	xfs_dqlock(dqp);
  	dqp->q_nrefs = 1;
  
  	qi->qi_dquots++;
  	mutex_unlock(&qi->qi_tree_lock);
  
  	return 0;
  }

  /* Check our input parameters. */
  static int
  xfs_qm_dqget_checks(
  	struct xfs_mount	*mp,

  	xfs_dqtype_t		type)

  {
  	if (WARN_ON_ONCE(!XFS_IS_QUOTA_RUNNING(mp)))
  		return -ESRCH;
  
  	switch (type) {

  	case XFS_DQTYPE_USER:

  		if (!XFS_IS_UQUOTA_ON(mp))
  			return -ESRCH;
  		return 0;

  	case XFS_DQTYPE_GROUP:

  		if (!XFS_IS_GQUOTA_ON(mp))
  			return -ESRCH;
  		return 0;

  	case XFS_DQTYPE_PROJ:

  		if (!XFS_IS_PQUOTA_ON(mp))
  			return -ESRCH;
  		return 0;
  	default:
  		WARN_ON_ONCE(0);
  		return -EINVAL;
  	}
  }

  /*

   * Given the file system, id, and type (UDQUOT/GDQUOT/PDQUOT), return a
   * locked dquot, doing an allocation (if requested) as needed.

   */
  int
  xfs_qm_dqget(

  	struct xfs_mount	*mp,
  	xfs_dqid_t		id,

  	xfs_dqtype_t		type,

  	bool			can_alloc,

  	struct xfs_dquot	**O_dqpp)

  {

  	struct xfs_quotainfo	*qi = mp->m_quotainfo;

  	struct radix_tree_root	*tree = xfs_dquot_tree(qi, type);

  	struct xfs_dquot	*dqp;
  	int			error;

  	error = xfs_qm_dqget_checks(mp, type);
  	if (error)
  		return error;

  restart:
  	dqp = xfs_qm_dqget_cache_lookup(mp, qi, tree, id);
  	if (dqp) {
  		*O_dqpp = dqp;
  		return 0;
  	}

  	error = xfs_qm_dqread(mp, id, type, can_alloc, &dqp);

  	if (error)
  		return error;
  
  	error = xfs_qm_dqget_cache_insert(mp, qi, tree, id, dqp);
  	if (error) {
  		/*
  		 * Duplicate found. Just throw away the new dquot and start
  		 * over.
  		 */
  		xfs_qm_dqdestroy(dqp);
  		XFS_STATS_INC(mp, xs_qm_dquot_dups);
  		goto restart;
  	}
  
  	trace_xfs_dqget_miss(dqp);
  	*O_dqpp = dqp;
  	return 0;
  }

  /*
   * Given a dquot id and type, read and initialize a dquot from the on-disk
   * metadata.  This function is only for use during quota initialization so
   * it ignores the dquot cache assuming that the dquot shrinker isn't set up.
   * The caller is responsible for _qm_dqdestroy'ing the returned dquot.
   */
  int
  xfs_qm_dqget_uncached(
  	struct xfs_mount	*mp,
  	xfs_dqid_t		id,

  	xfs_dqtype_t		type,

  	struct xfs_dquot	**dqpp)
  {
  	int			error;
  
  	error = xfs_qm_dqget_checks(mp, type);
  	if (error)
  		return error;
  
  	return xfs_qm_dqread(mp, id, type, 0, dqpp);
  }

  /* Return the quota id for a given inode and type. */
  xfs_dqid_t
  xfs_qm_id_for_quotatype(
  	struct xfs_inode	*ip,

  	xfs_dqtype_t		type)

  {
  	switch (type) {

  	case XFS_DQTYPE_USER:

  		return i_uid_read(VFS_I(ip));

  	case XFS_DQTYPE_GROUP:

  		return i_gid_read(VFS_I(ip));

  	case XFS_DQTYPE_PROJ:

  		return ip->i_d.di_projid;

  	}

  	ASSERT(0);
  	return 0;
  }
  
  /*
   * Return the dquot for a given inode and type.  If @can_alloc is true, then
   * allocate blocks if needed.  The inode's ILOCK must be held and it must not
   * have already had an inode attached.
   */
  int
  xfs_qm_dqget_inode(
  	struct xfs_inode	*ip,

  	xfs_dqtype_t		type,

  	bool			can_alloc,
  	struct xfs_dquot	**O_dqpp)
  {
  	struct xfs_mount	*mp = ip->i_mount;
  	struct xfs_quotainfo	*qi = mp->m_quotainfo;
  	struct radix_tree_root	*tree = xfs_dquot_tree(qi, type);
  	struct xfs_dquot	*dqp;
  	xfs_dqid_t		id;

  	int			error;
  
  	error = xfs_qm_dqget_checks(mp, type);
  	if (error)
  		return error;

  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
  	ASSERT(xfs_inode_dquot(ip, type) == NULL);
  
  	id = xfs_qm_id_for_quotatype(ip, type);

  
  restart:

  	dqp = xfs_qm_dqget_cache_lookup(mp, qi, tree, id);

  	if (dqp) {

  		*O_dqpp = dqp;
  		return 0;

  	}

  
  	/*
  	 * Dquot cache miss. We don't want to keep the inode lock across
  	 * a (potential) disk read. Also we don't want to deal with the lock
  	 * ordering between quotainode and this inode. OTOH, dropping the inode
  	 * lock here means dealing with a chown that can happen before
  	 * we re-acquire the lock.
  	 */

  	xfs_iunlock(ip, XFS_ILOCK_EXCL);

  	error = xfs_qm_dqread(mp, id, type, can_alloc, &dqp);

  	xfs_ilock(ip, XFS_ILOCK_EXCL);

  	if (error)
  		return error;

  	/*
  	 * A dquot could be attached to this inode by now, since we had
  	 * dropped the ilock.
  	 */
  	if (xfs_this_quota_on(mp, type)) {
  		struct xfs_dquot	*dqp1;
  
  		dqp1 = xfs_inode_dquot(ip, type);
  		if (dqp1) {

  			xfs_qm_dqdestroy(dqp);

  			dqp = dqp1;
  			xfs_dqlock(dqp);
  			goto dqret;

  		}

  	} else {
  		/* inode stays locked on return */
  		xfs_qm_dqdestroy(dqp);
  		return -ESRCH;

  	}

  	error = xfs_qm_dqget_cache_insert(mp, qi, tree, id, dqp);
  	if (error) {

  		/*

  		 * Duplicate found. Just throw away the new dquot and start
  		 * over.

  		 */

  		xfs_qm_dqdestroy(dqp);

  		XFS_STATS_INC(mp, xs_qm_dquot_dups);

  		goto restart;

  	}

  dqret:
  	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));

  	trace_xfs_dqget_miss(dqp);

  	*O_dqpp = dqp;

  	return 0;

  }

  /*

   * Starting at @id and progressing upwards, look for an initialized incore
   * dquot, lock it, and return it.
   */
  int
  xfs_qm_dqget_next(
  	struct xfs_mount	*mp,
  	xfs_dqid_t		id,

  	xfs_dqtype_t		type,

  	struct xfs_dquot	**dqpp)
  {
  	struct xfs_dquot	*dqp;
  	int			error = 0;
  
  	*dqpp = NULL;
  	for (; !error; error = xfs_dq_get_next_id(mp, type, &id)) {

  		error = xfs_qm_dqget(mp, id, type, false, &dqp);

  		if (error == -ENOENT)
  			continue;
  		else if (error != 0)
  			break;
  
  		if (!XFS_IS_DQUOT_UNINITIALIZED(dqp)) {
  			*dqpp = dqp;
  			return 0;
  		}
  
  		xfs_qm_dqput(dqp);
  	}
  
  	return error;
  }
  
  /*

   * Release a reference to the dquot (decrement ref-count) and unlock it.
   *
   * If there is a group quota attached to this dquot, carefully release that
   * too without tripping over deadlocks'n'stuff.
   */
  void
  xfs_qm_dqput(
  	struct xfs_dquot	*dqp)
  {
  	ASSERT(dqp->q_nrefs > 0);
  	ASSERT(XFS_DQ_IS_LOCKED(dqp));
  
  	trace_xfs_dqput(dqp);

  	if (--dqp->q_nrefs == 0) {
  		struct xfs_quotainfo	*qi = dqp->q_mount->m_quotainfo;
  		trace_xfs_dqput_free(dqp);
  
  		if (list_lru_add(&qi->qi_lru, &dqp->q_lru))

  			XFS_STATS_INC(dqp->q_mount, xs_qm_dquot_unused);

  	}
  	xfs_dqunlock(dqp);

  }
  
  /*
   * Release a dquot. Flush it if dirty, then dqput() it.
   * dquot must not be locked.
   */
  void
  xfs_qm_dqrele(

  	struct xfs_dquot	*dqp)

  {

  	if (!dqp)
  		return;

  	trace_xfs_dqrele(dqp);

  
  	xfs_dqlock(dqp);
  	/*
  	 * We don't care to flush it if the dquot is dirty here.
  	 * That will create stutters that we want to avoid.
  	 * Instead we do a delayed write when we try to reclaim
  	 * a dirty dquot. Also xfs_sync will take part of the burden...
  	 */
  	xfs_qm_dqput(dqp);
  }

  /*
   * This is the dquot flushing I/O completion routine.  It is called
   * from interrupt level when the buffer containing the dquot is
   * flushed to disk.  It is responsible for removing the dquot logitem
   * from the AIL if it has not been re-logged, and unlocking the dquot's
   * flush lock. This behavior is very similar to that of inodes..
   */

  static void

  xfs_qm_dqflush_done(

  	struct xfs_log_item	*lip)
  {

  	struct xfs_dq_logitem	*qip = (struct xfs_dq_logitem *)lip;

  	struct xfs_dquot	*dqp = qip->qli_dquot;

  	struct xfs_ail		*ailp = lip->li_ailp;

  	xfs_lsn_t		tail_lsn;

  
  	/*
  	 * We only want to pull the item from the AIL if its
  	 * location in the log has not changed since we started the flush.
  	 * Thus, we only bother if the dquot's lsn has
  	 * not changed. First we check the lsn outside the lock
  	 * since it's cheaper, and then we recheck while
  	 * holding the lock before removing the dquot from the AIL.
  	 */

  	if (test_bit(XFS_LI_IN_AIL, &lip->li_flags) &&

  	    ((lip->li_lsn == qip->qli_flush_lsn) ||

  	     test_bit(XFS_LI_FAILED, &lip->li_flags))) {

  		spin_lock(&ailp->ail_lock);

  		xfs_clear_li_failed(lip);

  		if (lip->li_lsn == qip->qli_flush_lsn) {

  			/* xfs_ail_update_finish() drops the AIL lock */
  			tail_lsn = xfs_ail_delete_one(ailp, lip);
  			xfs_ail_update_finish(ailp, tail_lsn);

  		} else {

  			spin_unlock(&ailp->ail_lock);

  		}

  	}
  
  	/*
  	 * Release the dq's flush lock since we're done with it.
  	 */
  	xfs_dqfunlock(dqp);
  }

  void

  xfs_buf_dquot_iodone(

  	struct xfs_buf		*bp)
  {
  	struct xfs_log_item	*lip, *n;
  
  	list_for_each_entry_safe(lip, n, &bp->b_li_list, li_bio_list) {
  		list_del_init(&lip->li_bio_list);
  		xfs_qm_dqflush_done(lip);
  	}
  }

  void
  xfs_buf_dquot_io_fail(
  	struct xfs_buf		*bp)
  {
  	struct xfs_log_item	*lip;
  
  	spin_lock(&bp->b_mount->m_ail->ail_lock);
  	list_for_each_entry(lip, &bp->b_li_list, li_bio_list)
  		xfs_set_li_failed(lip, bp);
  	spin_unlock(&bp->b_mount->m_ail->ail_lock);
  }

  /* Check incore dquot for errors before we flush. */
  static xfs_failaddr_t
  xfs_qm_dqflush_check(
  	struct xfs_dquot	*dqp)
  {

  	xfs_dqtype_t		type = xfs_dquot_type(dqp);

  	if (type != XFS_DQTYPE_USER &&
  	    type != XFS_DQTYPE_GROUP &&
  	    type != XFS_DQTYPE_PROJ)

  		return __this_address;

  	if (dqp->q_id == 0)
  		return NULL;

  	if (dqp->q_blk.softlimit && dqp->q_blk.count > dqp->q_blk.softlimit &&

  	    !dqp->q_blk.timer)

  		return __this_address;

  	if (dqp->q_ino.softlimit && dqp->q_ino.count > dqp->q_ino.softlimit &&

  	    !dqp->q_ino.timer)

  		return __this_address;

  	if (dqp->q_rtb.softlimit && dqp->q_rtb.count > dqp->q_rtb.softlimit &&

  	    !dqp->q_rtb.timer)

  		return __this_address;

  	/* bigtime flag should never be set on root dquots */
  	if (dqp->q_type & XFS_DQTYPE_BIGTIME) {
  		if (!xfs_sb_version_hasbigtime(&dqp->q_mount->m_sb))
  			return __this_address;
  		if (dqp->q_id == 0)
  			return __this_address;
  	}

  	return NULL;
  }

  /*
   * Write a modified dquot to disk.
   * The dquot must be locked and the flush lock too taken by caller.
   * The flush lock will not be unlocked until the dquot reaches the disk,
   * but the dquot is free to be unlocked and modified by the caller
   * in the interim. Dquot is still locked on return. This behavior is
   * identical to that of inodes.
   */
  int
  xfs_qm_dqflush(

  	struct xfs_dquot	*dqp,
  	struct xfs_buf		**bpp)

  {

  	struct xfs_mount	*mp = dqp->q_mount;

  	struct xfs_log_item	*lip = &dqp->q_logitem.qli_item;

  	struct xfs_buf		*bp;

  	struct xfs_dqblk	*dqblk;

  	xfs_failaddr_t		fa;

  	int			error;

  
  	ASSERT(XFS_DQ_IS_LOCKED(dqp));

  	ASSERT(!completion_done(&dqp->q_flush));

  	trace_xfs_dqflush(dqp);

  	*bpp = NULL;

  	xfs_qm_dqunpin_wait(dqp);
  
  	/*

  	 * Get the buffer containing the on-disk dquot

  	 */

  	error = xfs_trans_read_buf(mp, NULL, mp->m_ddev_targp, dqp->q_blkno,

  				   mp->m_quotainfo->qi_dqchunklen, XBF_TRYLOCK,
  				   &bp, &xfs_dquot_buf_ops);

  	if (error == -EAGAIN)

  		goto out_unlock;

  	if (error)
  		goto out_abort;

  	fa = xfs_qm_dqflush_check(dqp);
  	if (fa) {
  		xfs_alert(mp, "corrupt dquot ID 0x%x in memory at %pS",

  				dqp->q_id, fa);

  		xfs_buf_relse(bp);
  		error = -EFSCORRUPTED;
  		goto out_abort;
  	}

  	/* Flush the incore dquot to the ondisk buffer. */
  	dqblk = bp->b_addr + dqp->q_bufoffset;
  	xfs_dquot_to_disk(&dqblk->dd_diskdq, dqp);

  
  	/*
  	 * Clear the dirty field and remember the flush lsn for later use.
  	 */

  	dqp->q_flags &= ~XFS_DQFLAG_DIRTY;

  	xfs_trans_ail_copy_lsn(mp->m_ail, &dqp->q_logitem.qli_flush_lsn,
  					&dqp->q_logitem.qli_item.li_lsn);

  
  	/*

  	 * copy the lsn into the on-disk dquot now while we have the in memory
  	 * dquot here. This can't be done later in the write verifier as we
  	 * can't get access to the log item at that point in time.

  	 *
  	 * We also calculate the CRC here so that the on-disk dquot in the
  	 * buffer always has a valid CRC. This ensures there is no possibility
  	 * of a dquot without an up-to-date CRC getting to disk.

  	 */
  	if (xfs_sb_version_hascrc(&mp->m_sb)) {

  		dqblk->dd_lsn = cpu_to_be64(dqp->q_logitem.qli_item.li_lsn);
  		xfs_update_cksum((char *)dqblk, sizeof(struct xfs_dqblk),

  				 XFS_DQUOT_CRC_OFF);

  	}
  
  	/*

  	 * Attach the dquot to the buffer so that we can remove this dquot from
  	 * the AIL and release the flush lock once the dquot is synced to disk.

  	 */

  	bp->b_flags |= _XBF_DQUOTS;

  	list_add_tail(&dqp->q_logitem.qli_item.li_bio_list, &bp->b_li_list);

  	/*
  	 * If the buffer is pinned then push on the log so we won't
  	 * get stuck waiting in the write for too long.
  	 */

  	if (xfs_buf_ispinned(bp)) {

  		trace_xfs_dqflush_force(dqp);

  		xfs_log_force(mp, 0);

  	}

  	trace_xfs_dqflush_done(dqp);

  	*bpp = bp;
  	return 0;

  out_abort:

  	dqp->q_flags &= ~XFS_DQFLAG_DIRTY;

  	xfs_trans_ail_delete(lip, 0);

  	xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);

  out_unlock:
  	xfs_dqfunlock(dqp);

  	return error;

  }

  /*
   * Lock two xfs_dquot structures.
   *
   * To avoid deadlocks we always lock the quota structure with
   * the lowerd id first.
   */

  void
  xfs_dqlock2(

  	struct xfs_dquot	*d1,
  	struct xfs_dquot	*d2)

  {
  	if (d1 && d2) {
  		ASSERT(d1 != d2);

  		if (d1->q_id > d2->q_id) {

  			mutex_lock(&d2->q_qlock);
  			mutex_lock_nested(&d1->q_qlock, XFS_QLOCK_NESTED);

  		} else {

  			mutex_lock(&d1->q_qlock);
  			mutex_lock_nested(&d2->q_qlock, XFS_QLOCK_NESTED);

  		}

  	} else if (d1) {
  		mutex_lock(&d1->q_qlock);
  	} else if (d2) {
  		mutex_lock(&d2->q_qlock);

  	}
  }

  int __init
  xfs_qm_init(void)
  {

  	xfs_qm_dqzone = kmem_cache_create("xfs_dquot",
  					  sizeof(struct xfs_dquot),
  					  0, 0, NULL);

  	if (!xfs_qm_dqzone)
  		goto out;

  	xfs_qm_dqtrxzone = kmem_cache_create("xfs_dqtrx",
  					     sizeof(struct xfs_dquot_acct),
  					     0, 0, NULL);

  	if (!xfs_qm_dqtrxzone)
  		goto out_free_dqzone;
  
  	return 0;
  
  out_free_dqzone:

  	kmem_cache_destroy(xfs_qm_dqzone);

  out:
  	return -ENOMEM;
  }

  void

  xfs_qm_exit(void)
  {

  	kmem_cache_destroy(xfs_qm_dqtrxzone);
  	kmem_cache_destroy(xfs_qm_dqzone);

  }

  
  /*
   * Iterate every dquot of a particular type.  The caller must ensure that the
   * particular quota type is active.  iter_fn can return negative error codes,

   * or -ECANCELED to indicate that it wants to stop iterating.

   */
  int
  xfs_qm_dqiterate(
  	struct xfs_mount	*mp,

  	xfs_dqtype_t		type,

  	xfs_qm_dqiterate_fn	iter_fn,
  	void			*priv)
  {
  	struct xfs_dquot	*dq;
  	xfs_dqid_t		id = 0;
  	int			error;
  
  	do {

  		error = xfs_qm_dqget_next(mp, id, type, &dq);

  		if (error == -ENOENT)
  			return 0;
  		if (error)
  			return error;

  		error = iter_fn(dq, type, priv);

  		id = dq->q_id;

  		xfs_qm_dqput(dq);

  	} while (error == 0 && id != 0);
  
  	return error;
  }