Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1272 insertions, 0 deletions

diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c
new file mode 100644
index 000000000..59b2b2954
--- /dev/null
+++ b/fs/xfs/xfs_dquot.c
@@ -0,0 +1,1272 @@
+// 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_bmap_util.h"
+#include "xfs_alloc.h"
+#include "xfs_quota.h"
+#include "xfs_error.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_cksum.h"
+#include "xfs_trace.h"
+#include "xfs_log.h"
+#include "xfs_bmap_btree.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(
+	xfs_dquot_t	*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_zone_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_mount	*mp,
+	struct xfs_dquot	*dq)
+{
+	struct xfs_quotainfo	*q = mp->m_quotainfo;
+	struct xfs_disk_dquot	*d = &dq->q_core;
+	struct xfs_def_quota	*defq;
+	int			prealloc = 0;
+
+	ASSERT(d->d_id);
+	defq = xfs_get_defquota(dq, q);
+
+	if (defq->bsoftlimit && !d->d_blk_softlimit) {
+		d->d_blk_softlimit = cpu_to_be64(defq->bsoftlimit);
+		prealloc = 1;
+	}
+	if (defq->bhardlimit && !d->d_blk_hardlimit) {
+		d->d_blk_hardlimit = cpu_to_be64(defq->bhardlimit);
+		prealloc = 1;
+	}
+	if (defq->isoftlimit && !d->d_ino_softlimit)
+		d->d_ino_softlimit = cpu_to_be64(defq->isoftlimit);
+	if (defq->ihardlimit && !d->d_ino_hardlimit)
+		d->d_ino_hardlimit = cpu_to_be64(defq->ihardlimit);
+	if (defq->rtbsoftlimit && !d->d_rtb_softlimit)
+		d->d_rtb_softlimit = cpu_to_be64(defq->rtbsoftlimit);
+	if (defq->rtbhardlimit && !d->d_rtb_hardlimit)
+		d->d_rtb_hardlimit = cpu_to_be64(defq->rtbhardlimit);
+
+	if (prealloc)
+		xfs_dquot_set_prealloc_limits(dq);
+}
+
+/*
+ * 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(
+	xfs_mount_t		*mp,
+	xfs_disk_dquot_t	*d)
+{
+	ASSERT(d->d_id);
+
+#ifdef DEBUG
+	if (d->d_blk_hardlimit)
+		ASSERT(be64_to_cpu(d->d_blk_softlimit) <=
+		       be64_to_cpu(d->d_blk_hardlimit));
+	if (d->d_ino_hardlimit)
+		ASSERT(be64_to_cpu(d->d_ino_softlimit) <=
+		       be64_to_cpu(d->d_ino_hardlimit));
+	if (d->d_rtb_hardlimit)
+		ASSERT(be64_to_cpu(d->d_rtb_softlimit) <=
+		       be64_to_cpu(d->d_rtb_hardlimit));
+#endif
+
+	if (!d->d_btimer) {
+		if ((d->d_blk_softlimit &&
+		     (be64_to_cpu(d->d_bcount) >
+		      be64_to_cpu(d->d_blk_softlimit))) ||
+		    (d->d_blk_hardlimit &&
+		     (be64_to_cpu(d->d_bcount) >
+		      be64_to_cpu(d->d_blk_hardlimit)))) {
+			d->d_btimer = cpu_to_be32(get_seconds() +
+					mp->m_quotainfo->qi_btimelimit);
+		} else {
+			d->d_bwarns = 0;
+		}
+	} else {
+		if ((!d->d_blk_softlimit ||
+		     (be64_to_cpu(d->d_bcount) <=
+		      be64_to_cpu(d->d_blk_softlimit))) &&
+		    (!d->d_blk_hardlimit ||
+		    (be64_to_cpu(d->d_bcount) <=
+		     be64_to_cpu(d->d_blk_hardlimit)))) {
+			d->d_btimer = 0;
+		}
+	}
+
+	if (!d->d_itimer) {
+		if ((d->d_ino_softlimit &&
+		     (be64_to_cpu(d->d_icount) >
+		      be64_to_cpu(d->d_ino_softlimit))) ||
+		    (d->d_ino_hardlimit &&
+		     (be64_to_cpu(d->d_icount) >
+		      be64_to_cpu(d->d_ino_hardlimit)))) {
+			d->d_itimer = cpu_to_be32(get_seconds() +
+					mp->m_quotainfo->qi_itimelimit);
+		} else {
+			d->d_iwarns = 0;
+		}
+	} else {
+		if ((!d->d_ino_softlimit ||
+		     (be64_to_cpu(d->d_icount) <=
+		      be64_to_cpu(d->d_ino_softlimit)))  &&
+		    (!d->d_ino_hardlimit ||
+		     (be64_to_cpu(d->d_icount) <=
+		      be64_to_cpu(d->d_ino_hardlimit)))) {
+			d->d_itimer = 0;
+		}
+	}
+
+	if (!d->d_rtbtimer) {
+		if ((d->d_rtb_softlimit &&
+		     (be64_to_cpu(d->d_rtbcount) >
+		      be64_to_cpu(d->d_rtb_softlimit))) ||
+		    (d->d_rtb_hardlimit &&
+		     (be64_to_cpu(d->d_rtbcount) >
+		      be64_to_cpu(d->d_rtb_hardlimit)))) {
+			d->d_rtbtimer = cpu_to_be32(get_seconds() +
+					mp->m_quotainfo->qi_rtbtimelimit);
+		} else {
+			d->d_rtbwarns = 0;
+		}
+	} else {
+		if ((!d->d_rtb_softlimit ||
+		     (be64_to_cpu(d->d_rtbcount) <=
+		      be64_to_cpu(d->d_rtb_softlimit))) &&
+		    (!d->d_rtb_hardlimit ||
+		     (be64_to_cpu(d->d_rtbcount) <=
+		      be64_to_cpu(d->d_rtb_hardlimit)))) {
+			d->d_rtbtimer = 0;
+		}
+	}
+}
+
+/*
+ * initialize a buffer full of dquots and log the whole thing
+ */
+STATIC void
+xfs_qm_init_dquot_blk(
+	xfs_trans_t	*tp,
+	xfs_mount_t	*mp,
+	xfs_dqid_t	id,
+	uint		type,
+	xfs_buf_t	*bp)
+{
+	struct xfs_quotainfo	*q = mp->m_quotainfo;
+	xfs_dqblk_t	*d;
+	xfs_dqid_t	curid;
+	int		i;
+
+	ASSERT(tp);
+	ASSERT(xfs_buf_islocked(bp));
+
+	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_flags = type;
+		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,
+			    (type & XFS_DQ_USER ? XFS_BLF_UDQUOT_BUF :
+			    ((type & XFS_DQ_PROJ) ? XFS_BLF_PDQUOT_BUF :
+			     XFS_BLF_GDQUOT_BUF)));
+	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 = be64_to_cpu(dqp->q_core.d_blk_hardlimit);
+	dqp->q_prealloc_lo_wmark = be64_to_cpu(dqp->q_core.d_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;
+	struct xfs_inode	*quotip = xfs_quota_inode(mp, dqp->dq_flags);
+	int			nmaps = 1;
+	int			error;
+
+	trace_xfs_dqalloc(dqp);
+
+	xfs_ilock(quotip, XFS_ILOCK_EXCL);
+	if (!xfs_this_quota_on(dqp->q_mount, dqp->dq_flags)) {
+		/*
+		 * 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,
+			XFS_QM_DQALLOC_SPACE_RES(mp), &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) */
+	bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, dqp->q_blkno,
+			mp->m_quotainfo->qi_dqchunklen, 0);
+	if (!bp)
+		return -ENOMEM;
+	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, be32_to_cpu(dqp->q_core.d_id),
+			      dqp->dq_flags & XFS_DQ_ALLTYPES, 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;
+	struct xfs_inode	*quotip = xfs_quota_inode(mp, dqp->dq_flags);
+	uint			lock_mode;
+	int			nmaps = 1;
+	int			error;
+
+	lock_mode = xfs_ilock_data_map_shared(quotip);
+	if (!xfs_this_quota_on(mp, dqp->dq_flags)) {
+		/*
+		 * 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,
+	uint			type)
+{
+	struct xfs_dquot	*dqp;
+
+	dqp = kmem_zone_zalloc(xfs_qm_dqzone, KM_SLEEP);
+
+	dqp->dq_flags = type;
+	dqp->q_core.d_id = cpu_to_be32(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_DQ_USER:
+		/* uses the default lock class */
+		break;
+	case XFS_DQ_GROUP:
+		lockdep_set_class(&dqp->q_qlock, &xfs_dquot_group_class);
+		break;
+	case XFS_DQ_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 void
+xfs_dquot_from_disk(
+	struct xfs_dquot	*dqp,
+	struct xfs_buf		*bp)
+{
+	struct xfs_disk_dquot	*ddqp = bp->b_addr + dqp->q_bufoffset;
+
+	/* copy everything from disk dquot to the incore dquot */
+	memcpy(&dqp->q_core, ddqp, sizeof(xfs_disk_dquot_t));
+
+	/*
+	 * Reservation counters are defined as reservation plus current usage
+	 * to avoid having to add every time.
+	 */
+	dqp->q_res_bcount = be64_to_cpu(ddqp->d_bcount);
+	dqp->q_res_icount = be64_to_cpu(ddqp->d_icount);
+	dqp->q_res_rtbcount = be64_to_cpu(ddqp->d_rtbcount);
+
+	/* initialize the dquot speculative prealloc thresholds */
+	xfs_dquot_set_prealloc_limits(dqp);
+}
+
+/* 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,
+	uint			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));
+	xfs_dquot_from_disk(dqp, bp);
+
+	xfs_buf_relse(bp);
+	*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,
+	uint			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->dq_flags & XFS_DQ_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,
+	uint			type)
+{
+	if (WARN_ON_ONCE(!XFS_IS_QUOTA_RUNNING(mp)))
+		return -ESRCH;
+
+	switch (type) {
+	case XFS_DQ_USER:
+		if (!XFS_IS_UQUOTA_ON(mp))
+			return -ESRCH;
+		return 0;
+	case XFS_DQ_GROUP:
+		if (!XFS_IS_GQUOTA_ON(mp))
+			return -ESRCH;
+		return 0;
+	case XFS_DQ_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), return a a locked
+ * dquot, doing an allocation (if requested) as needed.
+ */
+int
+xfs_qm_dqget(
+	struct xfs_mount	*mp,
+	xfs_dqid_t		id,
+	uint			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,
+	uint			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,
+	uint			type)
+{
+	switch (type) {
+	case XFS_DQ_USER:
+		return ip->i_d.di_uid;
+	case XFS_DQ_GROUP:
+		return ip->i_d.di_gid;
+	case XFS_DQ_PROJ:
+		return xfs_get_projid(ip);
+	}
+	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,
+	uint			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,
+	uint			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(
+	xfs_dquot_t	*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_buf		*bp,
+	struct xfs_log_item	*lip)
+{
+	xfs_dq_logitem_t	*qip = (struct xfs_dq_logitem *)lip;
+	xfs_dquot_t		*dqp = qip->qli_dquot;
+	struct xfs_ail		*ailp = lip->li_ailp;
+
+	/*
+	 * 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))) {
+
+		/* xfs_trans_ail_delete() drops the AIL lock. */
+		spin_lock(&ailp->ail_lock);
+		if (lip->li_lsn == qip->qli_flush_lsn) {
+			xfs_trans_ail_delete(ailp, lip, SHUTDOWN_CORRUPT_INCORE);
+		} else {
+			/*
+			 * Clear the failed state since we are about to drop the
+			 * flush lock
+			 */
+			xfs_clear_li_failed(lip);
+			spin_unlock(&ailp->ail_lock);
+		}
+	}
+
+	/*
+	 * Release the dq's flush lock since we're done with it.
+	 */
+	xfs_dqfunlock(dqp);
+}
+
+/*
+ * 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_buf		*bp;
+	struct xfs_dqblk	*dqb;
+	struct xfs_disk_dquot	*ddqp;
+	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);
+
+	/*
+	 * This may have been unpinned because the filesystem is shutting
+	 * down forcibly. If that's the case we must not write this dquot
+	 * to disk, because the log record didn't make it to disk.
+	 *
+	 * We also have to remove the log item from the AIL in this case,
+	 * as we wait for an emptry AIL as part of the unmount process.
+	 */
+	if (XFS_FORCED_SHUTDOWN(mp)) {
+		struct xfs_log_item	*lip = &dqp->q_logitem.qli_item;
+		dqp->dq_flags &= ~XFS_DQ_DIRTY;
+
+		xfs_trans_ail_remove(lip, SHUTDOWN_CORRUPT_INCORE);
+
+		error = -EIO;
+		goto out_unlock;
+	}
+
+	/*
+	 * 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, 0, &bp,
+				   &xfs_dquot_buf_ops);
+	if (error)
+		goto out_unlock;
+
+	/*
+	 * Calculate the location of the dquot inside the buffer.
+	 */
+	dqb = bp->b_addr + dqp->q_bufoffset;
+	ddqp = &dqb->dd_diskdq;
+
+	/* sanity check the in-core structure before we flush */
+	fa = xfs_dquot_verify(mp, &dqp->q_core, be32_to_cpu(dqp->q_core.d_id),
+			      0);
+	if (fa) {
+		xfs_alert(mp, "corrupt dquot ID 0x%x in memory at %pS",
+				be32_to_cpu(dqp->q_core.d_id), fa);
+		xfs_buf_relse(bp);
+		xfs_dqfunlock(dqp);
+		xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
+		return -EIO;
+	}
+
+	/* This is the only portion of data that needs to persist */
+	memcpy(ddqp, &dqp->q_core, sizeof(xfs_disk_dquot_t));
+
+	/*
+	 * Clear the dirty field and remember the flush lsn for later use.
+	 */
+	dqp->dq_flags &= ~XFS_DQ_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)) {
+		dqb->dd_lsn = cpu_to_be64(dqp->q_logitem.qli_item.li_lsn);
+		xfs_update_cksum((char *)dqb, sizeof(struct xfs_dqblk),
+				 XFS_DQUOT_CRC_OFF);
+	}
+
+	/*
+	 * Attach an iodone routine so that we can remove this dquot from the
+	 * AIL and release the flush lock once the dquot is synced to disk.
+	 */
+	xfs_buf_attach_iodone(bp, xfs_qm_dqflush_done,
+				  &dqp->q_logitem.qli_item);
+
+	/*
+	 * 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_unlock:
+	xfs_dqfunlock(dqp);
+	return -EIO;
+}
+
+/*
+ * Lock two xfs_dquot structures.
+ *
+ * To avoid deadlocks we always lock the quota structure with
+ * the lowerd id first.
+ */
+void
+xfs_dqlock2(
+	xfs_dquot_t	*d1,
+	xfs_dquot_t	*d2)
+{
+	if (d1 && d2) {
+		ASSERT(d1 != d2);
+		if (be32_to_cpu(d1->q_core.d_id) >
+		    be32_to_cpu(d2->q_core.d_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_zone_init(sizeof(struct xfs_dquot), "xfs_dquot");
+	if (!xfs_qm_dqzone)
+		goto out;
+
+	xfs_qm_dqtrxzone =
+		kmem_zone_init(sizeof(struct xfs_dquot_acct), "xfs_dqtrx");
+	if (!xfs_qm_dqtrxzone)
+		goto out_free_dqzone;
+
+	return 0;
+
+out_free_dqzone:
+	kmem_zone_destroy(xfs_qm_dqzone);
+out:
+	return -ENOMEM;
+}
+
+void
+xfs_qm_exit(void)
+{
+	kmem_zone_destroy(xfs_qm_dqtrxzone);
+	kmem_zone_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 XFS_BTREE_QUERY_RANGE_ABORT to indicate that it wants to stop iterating.
+ */
+int
+xfs_qm_dqiterate(
+	struct xfs_mount	*mp,
+	uint			dqtype,
+	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, dqtype, &dq);
+		if (error == -ENOENT)
+			return 0;
+		if (error)
+			return error;
+
+		error = iter_fn(dq, dqtype, priv);
+		id = be32_to_cpu(dq->q_core.d_id);
+		xfs_qm_dqput(dq);
+		id++;
+	} while (error == 0 && id != 0);
+
+	return error;
+}