Linux 3.7-rc1

[deliverable/linux.git] / fs / gfs2 / quota.c

/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2007 Red Hat, Inc.  All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License version 2.
 */

/*
 * Quota change tags are associated with each transaction that allocates or
 * deallocates space.  Those changes are accumulated locally to each node (in a
 * per-node file) and then are periodically synced to the quota file.  This
 * avoids the bottleneck of constantly touching the quota file, but introduces
 * fuzziness in the current usage value of IDs that are being used on different
 * nodes in the cluster simultaneously.  So, it is possible for a user on
 * multiple nodes to overrun their quota, but that overrun is controlable.
 * Since quota tags are part of transactions, there is no need for a quota check
 * program to be run on node crashes or anything like that.
 *
 * There are couple of knobs that let the administrator manage the quota
 * fuzziness.  "quota_quantum" sets the maximum time a quota change can be
 * sitting on one node before being synced to the quota file.  (The default is
 * 60 seconds.)  Another knob, "quota_scale" controls how quickly the frequency
 * of quota file syncs increases as the user moves closer to their limit.  The
 * more frequent the syncs, the more accurate the quota enforcement, but that
 * means that there is more contention between the nodes for the quota file.
 * The default value is one.  This sets the maximum theoretical quota overrun
 * (with infinite node with infinite bandwidth) to twice the user's limit.  (In
 * practice, the maximum overrun you see should be much less.)  A "quota_scale"
 * number greater than one makes quota syncs more frequent and reduces the
 * maximum overrun.  Numbers less than one (but greater than zero) make quota
 * syncs less frequent.
 *
 * GFS quotas also use per-ID Lock Value Blocks (LVBs) to cache the contents of
 * the quota file, so it is not being constantly read.
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/sort.h>
#include <linux/fs.h>
#include <linux/bio.h>
#include <linux/gfs2_ondisk.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <linux/quota.h>
#include <linux/dqblk_xfs.h>

#include "gfs2.h"
#include "incore.h"
#include "bmap.h"
#include "glock.h"
#include "glops.h"
#include "log.h"
#include "meta_io.h"
#include "quota.h"
#include "rgrp.h"
#include "super.h"
#include "trans.h"
#include "inode.h"
#include "util.h"

#define QUOTA_USER 1
#define QUOTA_GROUP 0

struct gfs2_quota_change_host {
	u64 qc_change;
	u32 qc_flags; /* GFS2_QCF_... */
	u32 qc_id;
};

static LIST_HEAD(qd_lru_list);
static atomic_t qd_lru_count = ATOMIC_INIT(0);
static DEFINE_SPINLOCK(qd_lru_lock);

int gfs2_shrink_qd_memory(struct shrinker *shrink, struct shrink_control *sc)
{
	struct gfs2_quota_data *qd;
	struct gfs2_sbd *sdp;
	int nr_to_scan = sc->nr_to_scan;

	if (nr_to_scan == 0)
		goto out;

	if (!(sc->gfp_mask & __GFP_FS))
		return -1;

	spin_lock(&qd_lru_lock);
	while (nr_to_scan && !list_empty(&qd_lru_list)) {
		qd = list_entry(qd_lru_list.next,
				struct gfs2_quota_data, qd_reclaim);
		sdp = qd->qd_gl->gl_sbd;

		/* Free from the filesystem-specific list */
		list_del(&qd->qd_list);

		gfs2_assert_warn(sdp, !qd->qd_change);
		gfs2_assert_warn(sdp, !qd->qd_slot_count);
		gfs2_assert_warn(sdp, !qd->qd_bh_count);

		gfs2_glock_put(qd->qd_gl);
		atomic_dec(&sdp->sd_quota_count);

		/* Delete it from the common reclaim list */
		list_del_init(&qd->qd_reclaim);
		atomic_dec(&qd_lru_count);
		spin_unlock(&qd_lru_lock);
		kmem_cache_free(gfs2_quotad_cachep, qd);
		spin_lock(&qd_lru_lock);
		nr_to_scan--;
	}
	spin_unlock(&qd_lru_lock);

out:
	return (atomic_read(&qd_lru_count) * sysctl_vfs_cache_pressure) / 100;
}

static u64 qd2offset(struct gfs2_quota_data *qd)
{
	u64 offset;

	offset = 2 * (u64)qd->qd_id + !test_bit(QDF_USER, &qd->qd_flags);
	offset *= sizeof(struct gfs2_quota);

	return offset;
}

static int qd_alloc(struct gfs2_sbd *sdp, int user, u32 id,
		    struct gfs2_quota_data **qdp)
{
	struct gfs2_quota_data *qd;
	int error;

	qd = kmem_cache_zalloc(gfs2_quotad_cachep, GFP_NOFS);
	if (!qd)
		return -ENOMEM;

	atomic_set(&qd->qd_count, 1);
	qd->qd_id = id;
	if (user)
		set_bit(QDF_USER, &qd->qd_flags);
	qd->qd_slot = -1;
	INIT_LIST_HEAD(&qd->qd_reclaim);

	error = gfs2_glock_get(sdp, 2 * (u64)id + !user,
			      &gfs2_quota_glops, CREATE, &qd->qd_gl);
	if (error)
		goto fail;

	*qdp = qd;

	return 0;

fail:
	kmem_cache_free(gfs2_quotad_cachep, qd);
	return error;
}

static int qd_get(struct gfs2_sbd *sdp, int user, u32 id,
		  struct gfs2_quota_data **qdp)
{
	struct gfs2_quota_data *qd = NULL, *new_qd = NULL;
	int error, found;

	*qdp = NULL;

	for (;;) {
		found = 0;
		spin_lock(&qd_lru_lock);
		list_for_each_entry(qd, &sdp->sd_quota_list, qd_list) {
			if (qd->qd_id == id &&
			    !test_bit(QDF_USER, &qd->qd_flags) == !user) {
				if (!atomic_read(&qd->qd_count) &&
				    !list_empty(&qd->qd_reclaim)) {
					/* Remove it from reclaim list */
					list_del_init(&qd->qd_reclaim);
					atomic_dec(&qd_lru_count);
				}
				atomic_inc(&qd->qd_count);
				found = 1;
				break;
			}
		}

		if (!found)
			qd = NULL;

		if (!qd && new_qd) {
			qd = new_qd;
			list_add(&qd->qd_list, &sdp->sd_quota_list);
			atomic_inc(&sdp->sd_quota_count);
			new_qd = NULL;
		}

		spin_unlock(&qd_lru_lock);

		if (qd) {
			if (new_qd) {
				gfs2_glock_put(new_qd->qd_gl);
				kmem_cache_free(gfs2_quotad_cachep, new_qd);
			}
			*qdp = qd;
			return 0;
		}

		error = qd_alloc(sdp, user, id, &new_qd);
		if (error)
			return error;
	}
}

static void qd_hold(struct gfs2_quota_data *qd)
{
	struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;
	gfs2_assert(sdp, atomic_read(&qd->qd_count));
	atomic_inc(&qd->qd_count);
}

static void qd_put(struct gfs2_quota_data *qd)
{
	if (atomic_dec_and_lock(&qd->qd_count, &qd_lru_lock)) {
		/* Add to the reclaim list */
		list_add_tail(&qd->qd_reclaim, &qd_lru_list);
		atomic_inc(&qd_lru_count);
		spin_unlock(&qd_lru_lock);
	}
}

static int slot_get(struct gfs2_quota_data *qd)
{
	struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;
	unsigned int c, o = 0, b;
	unsigned char byte = 0;

	spin_lock(&qd_lru_lock);

	if (qd->qd_slot_count++) {
		spin_unlock(&qd_lru_lock);
		return 0;
	}

	for (c = 0; c < sdp->sd_quota_chunks; c++)
		for (o = 0; o < PAGE_SIZE; o++) {
			byte = sdp->sd_quota_bitmap[c][o];
			if (byte != 0xFF)
				goto found;
		}

	goto fail;

found:
	for (b = 0; b < 8; b++)
		if (!(byte & (1 << b)))
			break;
	qd->qd_slot = c * (8 * PAGE_SIZE) + o * 8 + b;

	if (qd->qd_slot >= sdp->sd_quota_slots)
		goto fail;

	sdp->sd_quota_bitmap[c][o] |= 1 << b;

	spin_unlock(&qd_lru_lock);

	return 0;

fail:
	qd->qd_slot_count--;
	spin_unlock(&qd_lru_lock);
	return -ENOSPC;
}

static void slot_hold(struct gfs2_quota_data *qd)
{
	struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;

	spin_lock(&qd_lru_lock);
	gfs2_assert(sdp, qd->qd_slot_count);
	qd->qd_slot_count++;
	spin_unlock(&qd_lru_lock);
}

static void slot_put(struct gfs2_quota_data *qd)
{
	struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;

	spin_lock(&qd_lru_lock);
	gfs2_assert(sdp, qd->qd_slot_count);
	if (!--qd->qd_slot_count) {
		gfs2_icbit_munge(sdp, sdp->sd_quota_bitmap, qd->qd_slot, 0);
		qd->qd_slot = -1;
	}
	spin_unlock(&qd_lru_lock);
}

static int bh_get(struct gfs2_quota_data *qd)
{
	struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;
	struct gfs2_inode *ip = GFS2_I(sdp->sd_qc_inode);
	unsigned int block, offset;
	struct buffer_head *bh;
	int error;
	struct buffer_head bh_map = { .b_state = 0, .b_blocknr = 0 };

	mutex_lock(&sdp->sd_quota_mutex);

	if (qd->qd_bh_count++) {
		mutex_unlock(&sdp->sd_quota_mutex);
		return 0;
	}

	block = qd->qd_slot / sdp->sd_qc_per_block;
	offset = qd->qd_slot % sdp->sd_qc_per_block;

	bh_map.b_size = 1 << ip->i_inode.i_blkbits;
	error = gfs2_block_map(&ip->i_inode, block, &bh_map, 0);
	if (error)
		goto fail;
	error = gfs2_meta_read(ip->i_gl, bh_map.b_blocknr, DIO_WAIT, &bh);
	if (error)
		goto fail;
	error = -EIO;
	if (gfs2_metatype_check(sdp, bh, GFS2_METATYPE_QC))
		goto fail_brelse;

	qd->qd_bh = bh;
	qd->qd_bh_qc = (struct gfs2_quota_change *)
		(bh->b_data + sizeof(struct gfs2_meta_header) +
		 offset * sizeof(struct gfs2_quota_change));

	mutex_unlock(&sdp->sd_quota_mutex);

	return 0;

fail_brelse:
	brelse(bh);
fail:
	qd->qd_bh_count--;
	mutex_unlock(&sdp->sd_quota_mutex);
	return error;
}

static void bh_put(struct gfs2_quota_data *qd)
{
	struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;

	mutex_lock(&sdp->sd_quota_mutex);
	gfs2_assert(sdp, qd->qd_bh_count);
	if (!--qd->qd_bh_count) {
		brelse(qd->qd_bh);
		qd->qd_bh = NULL;
		qd->qd_bh_qc = NULL;
	}
	mutex_unlock(&sdp->sd_quota_mutex);
}

static int qd_fish(struct gfs2_sbd *sdp, struct gfs2_quota_data **qdp)
{
	struct gfs2_quota_data *qd = NULL;
	int error;
	int found = 0;

	*qdp = NULL;

	if (sdp->sd_vfs->s_flags & MS_RDONLY)
		return 0;

	spin_lock(&qd_lru_lock);

	list_for_each_entry(qd, &sdp->sd_quota_list, qd_list) {
		if (test_bit(QDF_LOCKED, &qd->qd_flags) ||
		    !test_bit(QDF_CHANGE, &qd->qd_flags) ||
		    qd->qd_sync_gen >= sdp->sd_quota_sync_gen)
			continue;

		list_move_tail(&qd->qd_list, &sdp->sd_quota_list);

		set_bit(QDF_LOCKED, &qd->qd_flags);
		gfs2_assert_warn(sdp, atomic_read(&qd->qd_count));
		atomic_inc(&qd->qd_count);
		qd->qd_change_sync = qd->qd_change;
		gfs2_assert_warn(sdp, qd->qd_slot_count);
		qd->qd_slot_count++;
		found = 1;

		break;
	}

	if (!found)
		qd = NULL;

	spin_unlock(&qd_lru_lock);

	if (qd) {
		gfs2_assert_warn(sdp, qd->qd_change_sync);
		error = bh_get(qd);
		if (error) {
			clear_bit(QDF_LOCKED, &qd->qd_flags);
			slot_put(qd);
			qd_put(qd);
			return error;
		}
	}

	*qdp = qd;

	return 0;
}

static int qd_trylock(struct gfs2_quota_data *qd)
{
	struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;

	if (sdp->sd_vfs->s_flags & MS_RDONLY)
		return 0;

	spin_lock(&qd_lru_lock);

	if (test_bit(QDF_LOCKED, &qd->qd_flags) ||
	    !test_bit(QDF_CHANGE, &qd->qd_flags)) {
		spin_unlock(&qd_lru_lock);
		return 0;
	}

	list_move_tail(&qd->qd_list, &sdp->sd_quota_list);

	set_bit(QDF_LOCKED, &qd->qd_flags);
	gfs2_assert_warn(sdp, atomic_read(&qd->qd_count));
	atomic_inc(&qd->qd_count);
	qd->qd_change_sync = qd->qd_change;
	gfs2_assert_warn(sdp, qd->qd_slot_count);
	qd->qd_slot_count++;

	spin_unlock(&qd_lru_lock);

	gfs2_assert_warn(sdp, qd->qd_change_sync);
	if (bh_get(qd)) {
		clear_bit(QDF_LOCKED, &qd->qd_flags);
		slot_put(qd);
		qd_put(qd);
		return 0;
	}

	return 1;
}

static void qd_unlock(struct gfs2_quota_data *qd)
{
	gfs2_assert_warn(qd->qd_gl->gl_sbd,
			 test_bit(QDF_LOCKED, &qd->qd_flags));
	clear_bit(QDF_LOCKED, &qd->qd_flags);
	bh_put(qd);
	slot_put(qd);
	qd_put(qd);
}

static int qdsb_get(struct gfs2_sbd *sdp, int user, u32 id,
		    struct gfs2_quota_data **qdp)
{
	int error;

	error = qd_get(sdp, user, id, qdp);
	if (error)
		return error;

	error = slot_get(*qdp);
	if (error)
		goto fail;

	error = bh_get(*qdp);
	if (error)
		goto fail_slot;

	return 0;

fail_slot:
	slot_put(*qdp);
fail:
	qd_put(*qdp);
	return error;
}

static void qdsb_put(struct gfs2_quota_data *qd)
{
	bh_put(qd);
	slot_put(qd);
	qd_put(qd);
}

int gfs2_quota_hold(struct gfs2_inode *ip, u32 uid, u32 gid)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct gfs2_quota_data **qd;
	int error;

	if (ip->i_res == NULL)
		gfs2_rs_alloc(ip);

	qd = ip->i_res->rs_qa_qd;

	if (gfs2_assert_warn(sdp, !ip->i_res->rs_qa_qd_num) ||
	    gfs2_assert_warn(sdp, !test_bit(GIF_QD_LOCKED, &ip->i_flags)))
		return -EIO;

	if (sdp->sd_args.ar_quota == GFS2_QUOTA_OFF)
		return 0;

	error = qdsb_get(sdp, QUOTA_USER, ip->i_inode.i_uid, qd);
	if (error)
		goto out;
	ip->i_res->rs_qa_qd_num++;
	qd++;

	error = qdsb_get(sdp, QUOTA_GROUP, ip->i_inode.i_gid, qd);
	if (error)
		goto out;
	ip->i_res->rs_qa_qd_num++;
	qd++;

	if (uid != NO_QUOTA_CHANGE && uid != ip->i_inode.i_uid) {
		error = qdsb_get(sdp, QUOTA_USER, uid, qd);
		if (error)
			goto out;
		ip->i_res->rs_qa_qd_num++;
		qd++;
	}

	if (gid != NO_QUOTA_CHANGE && gid != ip->i_inode.i_gid) {
		error = qdsb_get(sdp, QUOTA_GROUP, gid, qd);
		if (error)
			goto out;
		ip->i_res->rs_qa_qd_num++;
		qd++;
	}

out:
	if (error)
		gfs2_quota_unhold(ip);
	return error;
}

void gfs2_quota_unhold(struct gfs2_inode *ip)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	unsigned int x;

	if (ip->i_res == NULL)
		return;
	gfs2_assert_warn(sdp, !test_bit(GIF_QD_LOCKED, &ip->i_flags));

	for (x = 0; x < ip->i_res->rs_qa_qd_num; x++) {
		qdsb_put(ip->i_res->rs_qa_qd[x]);
		ip->i_res->rs_qa_qd[x] = NULL;
	}
	ip->i_res->rs_qa_qd_num = 0;
}

static int sort_qd(const void *a, const void *b)
{
	const struct gfs2_quota_data *qd_a = *(const struct gfs2_quota_data **)a;
	const struct gfs2_quota_data *qd_b = *(const struct gfs2_quota_data **)b;

	if (!test_bit(QDF_USER, &qd_a->qd_flags) !=
	    !test_bit(QDF_USER, &qd_b->qd_flags)) {
		if (test_bit(QDF_USER, &qd_a->qd_flags))
			return -1;
		else
			return 1;
	}
	if (qd_a->qd_id < qd_b->qd_id)
		return -1;
	if (qd_a->qd_id > qd_b->qd_id)
		return 1;

	return 0;
}

static void do_qc(struct gfs2_quota_data *qd, s64 change)
{
	struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;
	struct gfs2_inode *ip = GFS2_I(sdp->sd_qc_inode);
	struct gfs2_quota_change *qc = qd->qd_bh_qc;
	s64 x;

	mutex_lock(&sdp->sd_quota_mutex);
	gfs2_trans_add_bh(ip->i_gl, qd->qd_bh, 1);

	if (!test_bit(QDF_CHANGE, &qd->qd_flags)) {
		qc->qc_change = 0;
		qc->qc_flags = 0;
		if (test_bit(QDF_USER, &qd->qd_flags))
			qc->qc_flags = cpu_to_be32(GFS2_QCF_USER);
		qc->qc_id = cpu_to_be32(qd->qd_id);
	}

	x = be64_to_cpu(qc->qc_change) + change;
	qc->qc_change = cpu_to_be64(x);

	spin_lock(&qd_lru_lock);
	qd->qd_change = x;
	spin_unlock(&qd_lru_lock);

	if (!x) {
		gfs2_assert_warn(sdp, test_bit(QDF_CHANGE, &qd->qd_flags));
		clear_bit(QDF_CHANGE, &qd->qd_flags);
		qc->qc_flags = 0;
		qc->qc_id = 0;
		slot_put(qd);
		qd_put(qd);
	} else if (!test_and_set_bit(QDF_CHANGE, &qd->qd_flags)) {
		qd_hold(qd);
		slot_hold(qd);
	}

	mutex_unlock(&sdp->sd_quota_mutex);
}

/**
 * gfs2_adjust_quota - adjust record of current block usage
 * @ip: The quota inode
 * @loc: Offset of the entry in the quota file
 * @change: The amount of usage change to record
 * @qd: The quota data
 * @fdq: The updated limits to record
 *
 * This function was mostly borrowed from gfs2_block_truncate_page which was
 * in turn mostly borrowed from ext3
 *
 * Returns: 0 or -ve on error
 */

static int gfs2_adjust_quota(struct gfs2_inode *ip, loff_t loc,
			     s64 change, struct gfs2_quota_data *qd,
			     struct fs_disk_quota *fdq)
{
	struct inode *inode = &ip->i_inode;
	struct gfs2_sbd *sdp = GFS2_SB(inode);
	struct address_space *mapping = inode->i_mapping;
	unsigned long index = loc >> PAGE_CACHE_SHIFT;
	unsigned offset = loc & (PAGE_CACHE_SIZE - 1);
	unsigned blocksize, iblock, pos;
	struct buffer_head *bh;
	struct page *page;
	void *kaddr, *ptr;
	struct gfs2_quota q, *qp;
	int err, nbytes;
	u64 size;

	if (gfs2_is_stuffed(ip)) {
		err = gfs2_unstuff_dinode(ip, NULL);
		if (err)
			return err;
	}

	memset(&q, 0, sizeof(struct gfs2_quota));
	err = gfs2_internal_read(ip, (char *)&q, &loc, sizeof(q));
	if (err < 0)
		return err;

	err = -EIO;
	qp = &q;
	qp->qu_value = be64_to_cpu(qp->qu_value);
	qp->qu_value += change;
	qp->qu_value = cpu_to_be64(qp->qu_value);
	qd->qd_qb.qb_value = qp->qu_value;
	if (fdq) {
		if (fdq->d_fieldmask & FS_DQ_BSOFT) {
			qp->qu_warn = cpu_to_be64(fdq->d_blk_softlimit >> sdp->sd_fsb2bb_shift);
			qd->qd_qb.qb_warn = qp->qu_warn;
		}
		if (fdq->d_fieldmask & FS_DQ_BHARD) {
			qp->qu_limit = cpu_to_be64(fdq->d_blk_hardlimit >> sdp->sd_fsb2bb_shift);
			qd->qd_qb.qb_limit = qp->qu_limit;
		}
		if (fdq->d_fieldmask & FS_DQ_BCOUNT) {
			qp->qu_value = cpu_to_be64(fdq->d_bcount >> sdp->sd_fsb2bb_shift);
			qd->qd_qb.qb_value = qp->qu_value;
		}
	}

	/* Write the quota into the quota file on disk */
	ptr = qp;
	nbytes = sizeof(struct gfs2_quota);
get_a_page:
	page = find_or_create_page(mapping, index, GFP_NOFS);
	if (!page)
		return -ENOMEM;

	blocksize = inode->i_sb->s_blocksize;
	iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);

	if (!page_has_buffers(page))
		create_empty_buffers(page, blocksize, 0);

	bh = page_buffers(page);
	pos = blocksize;
	while (offset >= pos) {
		bh = bh->b_this_page;
		iblock++;
		pos += blocksize;
	}

	if (!buffer_mapped(bh)) {
		gfs2_block_map(inode, iblock, bh, 1);
		if (!buffer_mapped(bh))
			goto unlock_out;
		/* If it's a newly allocated disk block for quota, zero it */
		if (buffer_new(bh))
			zero_user(page, pos - blocksize, bh->b_size);
	}

	if (PageUptodate(page))
		set_buffer_uptodate(bh);

	if (!buffer_uptodate(bh)) {
		ll_rw_block(READ | REQ_META, 1, &bh);
		wait_on_buffer(bh);
		if (!buffer_uptodate(bh))
			goto unlock_out;
	}

	gfs2_trans_add_bh(ip->i_gl, bh, 0);

	kaddr = kmap_atomic(page);
	if (offset + sizeof(struct gfs2_quota) > PAGE_CACHE_SIZE)
		nbytes = PAGE_CACHE_SIZE - offset;
	memcpy(kaddr + offset, ptr, nbytes);
	flush_dcache_page(page);
	kunmap_atomic(kaddr);
	unlock_page(page);
	page_cache_release(page);

	/* If quota straddles page boundary, we need to update the rest of the
	 * quota at the beginning of the next page */
	if ((offset + sizeof(struct gfs2_quota)) > PAGE_CACHE_SIZE) {
		ptr = ptr + nbytes;
		nbytes = sizeof(struct gfs2_quota) - nbytes;
		offset = 0;
		index++;
		goto get_a_page;
	}

	size = loc + sizeof(struct gfs2_quota);
	if (size > inode->i_size)
		i_size_write(inode, size);
	inode->i_mtime = inode->i_atime = CURRENT_TIME;
	mark_inode_dirty(inode);
	return 0;

unlock_out:
	unlock_page(page);
	page_cache_release(page);
	return err;
}

static int do_sync(unsigned int num_qd, struct gfs2_quota_data **qda)
{
	struct gfs2_sbd *sdp = (*qda)->qd_gl->gl_sbd;
	struct gfs2_inode *ip = GFS2_I(sdp->sd_quota_inode);
	unsigned int data_blocks, ind_blocks;
	struct gfs2_holder *ghs, i_gh;
	unsigned int qx, x;
	struct gfs2_quota_data *qd;
	unsigned reserved;
	loff_t offset;
	unsigned int nalloc = 0, blocks;
	int error;

	error = gfs2_rs_alloc(ip);
	if (error)
		return error;

	gfs2_write_calc_reserv(ip, sizeof(struct gfs2_quota),
			      &data_blocks, &ind_blocks);

	ghs = kcalloc(num_qd, sizeof(struct gfs2_holder), GFP_NOFS);
	if (!ghs)
		return -ENOMEM;

	sort(qda, num_qd, sizeof(struct gfs2_quota_data *), sort_qd, NULL);
	mutex_lock(&ip->i_inode.i_mutex);
	for (qx = 0; qx < num_qd; qx++) {
		error = gfs2_glock_nq_init(qda[qx]->qd_gl, LM_ST_EXCLUSIVE,
					   GL_NOCACHE, &ghs[qx]);
		if (error)
			goto out;
	}

	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &i_gh);
	if (error)
		goto out;

	for (x = 0; x < num_qd; x++) {
		offset = qd2offset(qda[x]);
		if (gfs2_write_alloc_required(ip, offset,
					      sizeof(struct gfs2_quota)))
			nalloc++;
	}

	/* 
	 * 1 blk for unstuffing inode if stuffed. We add this extra
	 * block to the reservation unconditionally. If the inode
	 * doesn't need unstuffing, the block will be released to the 
	 * rgrp since it won't be allocated during the transaction
	 */
	/* +3 in the end for unstuffing block, inode size update block
	 * and another block in case quota straddles page boundary and 
	 * two blocks need to be updated instead of 1 */
	blocks = num_qd * data_blocks + RES_DINODE + num_qd + 3;

	reserved = 1 + (nalloc * (data_blocks + ind_blocks));
	error = gfs2_inplace_reserve(ip, reserved);
	if (error)
		goto out_alloc;

	if (nalloc)
		blocks += gfs2_rg_blocks(ip, reserved) + nalloc * ind_blocks + RES_STATFS;

	error = gfs2_trans_begin(sdp, blocks, 0);
	if (error)
		goto out_ipres;

	for (x = 0; x < num_qd; x++) {
		qd = qda[x];
		offset = qd2offset(qd);
		error = gfs2_adjust_quota(ip, offset, qd->qd_change_sync, qd, NULL);
		if (error)
			goto out_end_trans;

		do_qc(qd, -qd->qd_change_sync);
		set_bit(QDF_REFRESH, &qd->qd_flags);
	}

	error = 0;

out_end_trans:
	gfs2_trans_end(sdp);
out_ipres:
	gfs2_inplace_release(ip);
out_alloc:
	gfs2_glock_dq_uninit(&i_gh);
out:
	while (qx--)
		gfs2_glock_dq_uninit(&ghs[qx]);
	mutex_unlock(&ip->i_inode.i_mutex);
	kfree(ghs);
	gfs2_log_flush(ip->i_gl->gl_sbd, ip->i_gl);
	return error;
}

static int update_qd(struct gfs2_sbd *sdp, struct gfs2_quota_data *qd)
{
	struct gfs2_inode *ip = GFS2_I(sdp->sd_quota_inode);
	struct gfs2_quota q;
	struct gfs2_quota_lvb *qlvb;
	loff_t pos;
	int error;

	memset(&q, 0, sizeof(struct gfs2_quota));
	pos = qd2offset(qd);
	error = gfs2_internal_read(ip, (char *)&q, &pos, sizeof(q));
	if (error < 0)
		return error;

	qlvb = (struct gfs2_quota_lvb *)qd->qd_gl->gl_lvb;
	qlvb->qb_magic = cpu_to_be32(GFS2_MAGIC);
	qlvb->__pad = 0;
	qlvb->qb_limit = q.qu_limit;
	qlvb->qb_warn = q.qu_warn;
	qlvb->qb_value = q.qu_value;
	qd->qd_qb = *qlvb;

	return 0;
}

static int do_glock(struct gfs2_quota_data *qd, int force_refresh,
		    struct gfs2_holder *q_gh)
{
	struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;
	struct gfs2_inode *ip = GFS2_I(sdp->sd_quota_inode);
	struct gfs2_holder i_gh;
	int error;

restart:
	error = gfs2_glock_nq_init(qd->qd_gl, LM_ST_SHARED, 0, q_gh);
	if (error)
		return error;

	qd->qd_qb = *(struct gfs2_quota_lvb *)qd->qd_gl->gl_lvb;

	if (force_refresh || qd->qd_qb.qb_magic != cpu_to_be32(GFS2_MAGIC)) {
		gfs2_glock_dq_uninit(q_gh);
		error = gfs2_glock_nq_init(qd->qd_gl, LM_ST_EXCLUSIVE,
					   GL_NOCACHE, q_gh);
		if (error)
			return error;

		error = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, 0, &i_gh);
		if (error)
			goto fail;

		error = update_qd(sdp, qd);
		if (error)
			goto fail_gunlock;

		gfs2_glock_dq_uninit(&i_gh);
		gfs2_glock_dq_uninit(q_gh);
		force_refresh = 0;
		goto restart;
	}

	return 0;

fail_gunlock:
	gfs2_glock_dq_uninit(&i_gh);
fail:
	gfs2_glock_dq_uninit(q_gh);
	return error;
}

int gfs2_quota_lock(struct gfs2_inode *ip, u32 uid, u32 gid)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct gfs2_quota_data *qd;
	unsigned int x;
	int error = 0;

	error = gfs2_quota_hold(ip, uid, gid);
	if (error)
		return error;

	if (capable(CAP_SYS_RESOURCE) ||
	    sdp->sd_args.ar_quota != GFS2_QUOTA_ON)
		return 0;

	sort(ip->i_res->rs_qa_qd, ip->i_res->rs_qa_qd_num,
	     sizeof(struct gfs2_quota_data *), sort_qd, NULL);

	for (x = 0; x < ip->i_res->rs_qa_qd_num; x++) {
		int force = NO_FORCE;
		qd = ip->i_res->rs_qa_qd[x];
		if (test_and_clear_bit(QDF_REFRESH, &qd->qd_flags))
			force = FORCE;
		error = do_glock(qd, force, &ip->i_res->rs_qa_qd_ghs[x]);
		if (error)
			break;
	}

	if (!error)
		set_bit(GIF_QD_LOCKED, &ip->i_flags);
	else {
		while (x--)
			gfs2_glock_dq_uninit(&ip->i_res->rs_qa_qd_ghs[x]);
		gfs2_quota_unhold(ip);
	}

	return error;
}

static int need_sync(struct gfs2_quota_data *qd)
{
	struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;
	struct gfs2_tune *gt = &sdp->sd_tune;
	s64 value;
	unsigned int num, den;
	int do_sync = 1;

	if (!qd->qd_qb.qb_limit)
		return 0;

	spin_lock(&qd_lru_lock);
	value = qd->qd_change;
	spin_unlock(&qd_lru_lock);

	spin_lock(&gt->gt_spin);
	num = gt->gt_quota_scale_num;
	den = gt->gt_quota_scale_den;
	spin_unlock(&gt->gt_spin);

	if (value < 0)
		do_sync = 0;
	else if ((s64)be64_to_cpu(qd->qd_qb.qb_value) >=
		 (s64)be64_to_cpu(qd->qd_qb.qb_limit))
		do_sync = 0;
	else {
		value *= gfs2_jindex_size(sdp) * num;
		value = div_s64(value, den);
		value += (s64)be64_to_cpu(qd->qd_qb.qb_value);
		if (value < (s64)be64_to_cpu(qd->qd_qb.qb_limit))
			do_sync = 0;
	}

	return do_sync;
}

void gfs2_quota_unlock(struct gfs2_inode *ip)
{
	struct gfs2_quota_data *qda[4];
	unsigned int count = 0;
	unsigned int x;

	if (!test_and_clear_bit(GIF_QD_LOCKED, &ip->i_flags))
		goto out;

	for (x = 0; x < ip->i_res->rs_qa_qd_num; x++) {
		struct gfs2_quota_data *qd;
		int sync;

		qd = ip->i_res->rs_qa_qd[x];
		sync = need_sync(qd);

		gfs2_glock_dq_uninit(&ip->i_res->rs_qa_qd_ghs[x]);

		if (sync && qd_trylock(qd))
			qda[count++] = qd;
	}

	if (count) {
		do_sync(count, qda);
		for (x = 0; x < count; x++)
			qd_unlock(qda[x]);
	}

out:
	gfs2_quota_unhold(ip);
}

#define MAX_LINE 256

static int print_message(struct gfs2_quota_data *qd, char *type)
{
	struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;

	printk(KERN_INFO "GFS2: fsid=%s: quota %s for %s %u\n",
	       sdp->sd_fsname, type,
	       (test_bit(QDF_USER, &qd->qd_flags)) ? "user" : "group",
	       qd->qd_id);

	return 0;
}

int gfs2_quota_check(struct gfs2_inode *ip, u32 uid, u32 gid)
{
	struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
	struct gfs2_quota_data *qd;
	s64 value;
	unsigned int x;
	int error = 0;

	if (!test_bit(GIF_QD_LOCKED, &ip->i_flags))
		return 0;

        if (sdp->sd_args.ar_quota != GFS2_QUOTA_ON)
                return 0;

	for (x = 0; x < ip->i_res->rs_qa_qd_num; x++) {
		qd = ip->i_res->rs_qa_qd[x];

		if (!((qd->qd_id == uid && test_bit(QDF_USER, &qd->qd_flags)) ||
		      (qd->qd_id == gid && !test_bit(QDF_USER, &qd->qd_flags))))
			continue;

		value = (s64)be64_to_cpu(qd->qd_qb.qb_value);
		spin_lock(&qd_lru_lock);
		value += qd->qd_change;
		spin_unlock(&qd_lru_lock);

		if (be64_to_cpu(qd->qd_qb.qb_limit) && (s64)be64_to_cpu(qd->qd_qb.qb_limit) < value) {
			print_message(qd, "exceeded");
			quota_send_warning(make_kqid(&init_user_ns,
						     test_bit(QDF_USER, &qd->qd_flags) ?
						     USRQUOTA : GRPQUOTA,
						     qd->qd_id),
					   sdp->sd_vfs->s_dev, QUOTA_NL_BHARDWARN);

			error = -EDQUOT;
			break;
		} else if (be64_to_cpu(qd->qd_qb.qb_warn) &&
			   (s64)be64_to_cpu(qd->qd_qb.qb_warn) < value &&
			   time_after_eq(jiffies, qd->qd_last_warn +
					 gfs2_tune_get(sdp,
						gt_quota_warn_period) * HZ)) {
			quota_send_warning(make_kqid(&init_user_ns,
						     test_bit(QDF_USER, &qd->qd_flags) ?
						     USRQUOTA : GRPQUOTA,
						     qd->qd_id),
					   sdp->sd_vfs->s_dev, QUOTA_NL_BSOFTWARN);
			error = print_message(qd, "warning");
			qd->qd_last_warn = jiffies;
		}
	}

	return error;
}

void gfs2_quota_change(struct gfs2_inode *ip, s64 change,
		       u32 uid, u32 gid)
{
	struct gfs2_quota_data *qd;
	unsigned int x;

	if (gfs2_assert_warn(GFS2_SB(&ip->i_inode), change))
		return;
	if (ip->i_diskflags & GFS2_DIF_SYSTEM)
		return;

	for (x = 0; x < ip->i_res->rs_qa_qd_num; x++) {
		qd = ip->i_res->rs_qa_qd[x];

		if ((qd->qd_id == uid && test_bit(QDF_USER, &qd->qd_flags)) ||
		    (qd->qd_id == gid && !test_bit(QDF_USER, &qd->qd_flags))) {
			do_qc(qd, change);
		}
	}
}

int gfs2_quota_sync(struct super_block *sb, int type)
{
	struct gfs2_sbd *sdp = sb->s_fs_info;
	struct gfs2_quota_data **qda;
	unsigned int max_qd = gfs2_tune_get(sdp, gt_quota_simul_sync);
	unsigned int num_qd;
	unsigned int x;
	int error = 0;

	sdp->sd_quota_sync_gen++;

	qda = kcalloc(max_qd, sizeof(struct gfs2_quota_data *), GFP_KERNEL);
	if (!qda)
		return -ENOMEM;

	do {
		num_qd = 0;

		for (;;) {
			error = qd_fish(sdp, qda + num_qd);
			if (error || !qda[num_qd])
				break;
			if (++num_qd == max_qd)
				break;
		}

		if (num_qd) {
			if (!error)
				error = do_sync(num_qd, qda);
			if (!error)
				for (x = 0; x < num_qd; x++)
					qda[x]->qd_sync_gen =
						sdp->sd_quota_sync_gen;

			for (x = 0; x < num_qd; x++)
				qd_unlock(qda[x]);
		}
	} while (!error && num_qd == max_qd);

	kfree(qda);

	return error;
}

static int gfs2_quota_sync_timeo(struct super_block *sb, int type)
{
	return gfs2_quota_sync(sb, type);
}

int gfs2_quota_refresh(struct gfs2_sbd *sdp, int user, u32 id)
{
	struct gfs2_quota_data *qd;
	struct gfs2_holder q_gh;
	int error;

	error = qd_get(sdp, user, id, &qd);
	if (error)
		return error;

	error = do_glock(qd, FORCE, &q_gh);
	if (!error)
		gfs2_glock_dq_uninit(&q_gh);

	qd_put(qd);
	return error;
}

static void gfs2_quota_change_in(struct gfs2_quota_change_host *qc, const void *buf)
{
	const struct gfs2_quota_change *str = buf;

	qc->qc_change = be64_to_cpu(str->qc_change);
	qc->qc_flags = be32_to_cpu(str->qc_flags);
	qc->qc_id = be32_to_cpu(str->qc_id);
}

int gfs2_quota_init(struct gfs2_sbd *sdp)
{
	struct gfs2_inode *ip = GFS2_I(sdp->sd_qc_inode);
	u64 size = i_size_read(sdp->sd_qc_inode);
	unsigned int blocks = size >> sdp->sd_sb.sb_bsize_shift;
	unsigned int x, slot = 0;
	unsigned int found = 0;
	u64 dblock;
	u32 extlen = 0;
	int error;

	if (gfs2_check_internal_file_size(sdp->sd_qc_inode, 1, 64 << 20))
		return -EIO;

	sdp->sd_quota_slots = blocks * sdp->sd_qc_per_block;
	sdp->sd_quota_chunks = DIV_ROUND_UP(sdp->sd_quota_slots, 8 * PAGE_SIZE);

	error = -ENOMEM;

	sdp->sd_quota_bitmap = kcalloc(sdp->sd_quota_chunks,
				       sizeof(unsigned char *), GFP_NOFS);
	if (!sdp->sd_quota_bitmap)
		return error;

	for (x = 0; x < sdp->sd_quota_chunks; x++) {
		sdp->sd_quota_bitmap[x] = kzalloc(PAGE_SIZE, GFP_NOFS);
		if (!sdp->sd_quota_bitmap[x])
			goto fail;
	}

	for (x = 0; x < blocks; x++) {
		struct buffer_head *bh;
		unsigned int y;

		if (!extlen) {
			int new = 0;
			error = gfs2_extent_map(&ip->i_inode, x, &new, &dblock, &extlen);
			if (error)
				goto fail;
		}
		error = -EIO;
		bh = gfs2_meta_ra(ip->i_gl, dblock, extlen);
		if (!bh)
			goto fail;
		if (gfs2_metatype_check(sdp, bh, GFS2_METATYPE_QC)) {
			brelse(bh);
			goto fail;
		}

		for (y = 0; y < sdp->sd_qc_per_block && slot < sdp->sd_quota_slots;
		     y++, slot++) {
			struct gfs2_quota_change_host qc;
			struct gfs2_quota_data *qd;

			gfs2_quota_change_in(&qc, bh->b_data +
					  sizeof(struct gfs2_meta_header) +
					  y * sizeof(struct gfs2_quota_change));
			if (!qc.qc_change)
				continue;

			error = qd_alloc(sdp, (qc.qc_flags & GFS2_QCF_USER),
					 qc.qc_id, &qd);
			if (error) {
				brelse(bh);
				goto fail;
			}

			set_bit(QDF_CHANGE, &qd->qd_flags);
			qd->qd_change = qc.qc_change;
			qd->qd_slot = slot;
			qd->qd_slot_count = 1;

			spin_lock(&qd_lru_lock);
			gfs2_icbit_munge(sdp, sdp->sd_quota_bitmap, slot, 1);
			list_add(&qd->qd_list, &sdp->sd_quota_list);
			atomic_inc(&sdp->sd_quota_count);
			spin_unlock(&qd_lru_lock);

			found++;
		}

		brelse(bh);
		dblock++;
		extlen--;
	}

	if (found)
		fs_info(sdp, "found %u quota changes\n", found);

	return 0;

fail:
	gfs2_quota_cleanup(sdp);
	return error;
}

void gfs2_quota_cleanup(struct gfs2_sbd *sdp)
{
	struct list_head *head = &sdp->sd_quota_list;
	struct gfs2_quota_data *qd;
	unsigned int x;

	spin_lock(&qd_lru_lock);
	while (!list_empty(head)) {
		qd = list_entry(head->prev, struct gfs2_quota_data, qd_list);

		if (atomic_read(&qd->qd_count) > 1 ||
		    (atomic_read(&qd->qd_count) &&
		     !test_bit(QDF_CHANGE, &qd->qd_flags))) {
			list_move(&qd->qd_list, head);
			spin_unlock(&qd_lru_lock);
			schedule();
			spin_lock(&qd_lru_lock);
			continue;
		}

		list_del(&qd->qd_list);
		/* Also remove if this qd exists in the reclaim list */
		if (!list_empty(&qd->qd_reclaim)) {
			list_del_init(&qd->qd_reclaim);
			atomic_dec(&qd_lru_count);
		}
		atomic_dec(&sdp->sd_quota_count);
		spin_unlock(&qd_lru_lock);

		if (!atomic_read(&qd->qd_count)) {
			gfs2_assert_warn(sdp, !qd->qd_change);
			gfs2_assert_warn(sdp, !qd->qd_slot_count);
		} else
			gfs2_assert_warn(sdp, qd->qd_slot_count == 1);
		gfs2_assert_warn(sdp, !qd->qd_bh_count);

		gfs2_glock_put(qd->qd_gl);
		kmem_cache_free(gfs2_quotad_cachep, qd);

		spin_lock(&qd_lru_lock);
	}
	spin_unlock(&qd_lru_lock);

	gfs2_assert_warn(sdp, !atomic_read(&sdp->sd_quota_count));

	if (sdp->sd_quota_bitmap) {
		for (x = 0; x < sdp->sd_quota_chunks; x++)
			kfree(sdp->sd_quota_bitmap[x]);
		kfree(sdp->sd_quota_bitmap);
	}
}

static void quotad_error(struct gfs2_sbd *sdp, const char *msg, int error)
{
	if (error == 0 || error == -EROFS)
		return;
	if (!test_bit(SDF_SHUTDOWN, &sdp->sd_flags))
		fs_err(sdp, "gfs2_quotad: %s error %d\n", msg, error);
}

static void quotad_check_timeo(struct gfs2_sbd *sdp, const char *msg,
			       int (*fxn)(struct super_block *sb, int type),
			       unsigned long t, unsigned long *timeo,
			       unsigned int *new_timeo)
{
	if (t >= *timeo) {
		int error = fxn(sdp->sd_vfs, 0);
		quotad_error(sdp, msg, error);
		*timeo = gfs2_tune_get_i(&sdp->sd_tune, new_timeo) * HZ;
	} else {
		*timeo -= t;
	}
}

static void quotad_check_trunc_list(struct gfs2_sbd *sdp)
{
	struct gfs2_inode *ip;

	while(1) {
		ip = NULL;
		spin_lock(&sdp->sd_trunc_lock);
		if (!list_empty(&sdp->sd_trunc_list)) {
			ip = list_entry(sdp->sd_trunc_list.next,
					struct gfs2_inode, i_trunc_list);
			list_del_init(&ip->i_trunc_list);
		}
		spin_unlock(&sdp->sd_trunc_lock);
		if (ip == NULL)
			return;
		gfs2_glock_finish_truncate(ip);
	}
}

void gfs2_wake_up_statfs(struct gfs2_sbd *sdp) {
	if (!sdp->sd_statfs_force_sync) {
		sdp->sd_statfs_force_sync = 1;
		wake_up(&sdp->sd_quota_wait);
	}
}


/**
 * gfs2_quotad - Write cached quota changes into the quota file
 * @sdp: Pointer to GFS2 superblock
 *
 */

int gfs2_quotad(void *data)
{
	struct gfs2_sbd *sdp = data;
	struct gfs2_tune *tune = &sdp->sd_tune;
	unsigned long statfs_timeo = 0;
	unsigned long quotad_timeo = 0;
	unsigned long t = 0;
	DEFINE_WAIT(wait);
	int empty;

	while (!kthread_should_stop()) {

		/* Update the master statfs file */
		if (sdp->sd_statfs_force_sync) {
			int error = gfs2_statfs_sync(sdp->sd_vfs, 0);
			quotad_error(sdp, "statfs", error);
			statfs_timeo = gfs2_tune_get(sdp, gt_statfs_quantum) * HZ;
		}
		else
			quotad_check_timeo(sdp, "statfs", gfs2_statfs_sync, t,
				   	   &statfs_timeo,
					   &tune->gt_statfs_quantum);

		/* Update quota file */
		quotad_check_timeo(sdp, "sync", gfs2_quota_sync_timeo, t,
				   &quotad_timeo, &tune->gt_quota_quantum);

		/* Check for & recover partially truncated inodes */
		quotad_check_trunc_list(sdp);

		try_to_freeze();

		t = min(quotad_timeo, statfs_timeo);

		prepare_to_wait(&sdp->sd_quota_wait, &wait, TASK_INTERRUPTIBLE);
		spin_lock(&sdp->sd_trunc_lock);
		empty = list_empty(&sdp->sd_trunc_list);
		spin_unlock(&sdp->sd_trunc_lock);
		if (empty && !sdp->sd_statfs_force_sync)
			t -= schedule_timeout(t);
		else
			t = 0;
		finish_wait(&sdp->sd_quota_wait, &wait);
	}

	return 0;
}

static int gfs2_quota_get_xstate(struct super_block *sb,
				 struct fs_quota_stat *fqs)
{
	struct gfs2_sbd *sdp = sb->s_fs_info;

	memset(fqs, 0, sizeof(struct fs_quota_stat));
	fqs->qs_version = FS_QSTAT_VERSION;

	switch (sdp->sd_args.ar_quota) {
	case GFS2_QUOTA_ON:
		fqs->qs_flags |= (FS_QUOTA_UDQ_ENFD | FS_QUOTA_GDQ_ENFD);
		/*FALLTHRU*/
	case GFS2_QUOTA_ACCOUNT:
		fqs->qs_flags |= (FS_QUOTA_UDQ_ACCT | FS_QUOTA_GDQ_ACCT);
		break;
	case GFS2_QUOTA_OFF:
		break;
	}

	if (sdp->sd_quota_inode) {
		fqs->qs_uquota.qfs_ino = GFS2_I(sdp->sd_quota_inode)->i_no_addr;
		fqs->qs_uquota.qfs_nblks = sdp->sd_quota_inode->i_blocks;
	}
	fqs->qs_uquota.qfs_nextents = 1; /* unsupported */
	fqs->qs_gquota = fqs->qs_uquota; /* its the same inode in both cases */
	fqs->qs_incoredqs = atomic_read(&qd_lru_count);
	return 0;
}

static int gfs2_get_dqblk(struct super_block *sb, struct kqid qid,
			  struct fs_disk_quota *fdq)
{
	struct gfs2_sbd *sdp = sb->s_fs_info;
	struct gfs2_quota_lvb *qlvb;
	struct gfs2_quota_data *qd;
	struct gfs2_holder q_gh;
	int error;
	int type;

	memset(fdq, 0, sizeof(struct fs_disk_quota));

	if (sdp->sd_args.ar_quota == GFS2_QUOTA_OFF)
		return -ESRCH; /* Crazy XFS error code */

	if (qid.type == USRQUOTA)
		type = QUOTA_USER;
	else if (qid.type == GRPQUOTA)
		type = QUOTA_GROUP;
	else
		return -EINVAL;

	error = qd_get(sdp, type, from_kqid(&init_user_ns, qid), &qd);
	if (error)
		return error;
	error = do_glock(qd, FORCE, &q_gh);
	if (error)
		goto out;

	qlvb = (struct gfs2_quota_lvb *)qd->qd_gl->gl_lvb;
	fdq->d_version = FS_DQUOT_VERSION;
	fdq->d_flags = (type == QUOTA_USER) ? FS_USER_QUOTA : FS_GROUP_QUOTA;
	fdq->d_id = from_kqid(&init_user_ns, qid);
	fdq->d_blk_hardlimit = be64_to_cpu(qlvb->qb_limit) << sdp->sd_fsb2bb_shift;
	fdq->d_blk_softlimit = be64_to_cpu(qlvb->qb_warn) << sdp->sd_fsb2bb_shift;
	fdq->d_bcount = be64_to_cpu(qlvb->qb_value) << sdp->sd_fsb2bb_shift;

	gfs2_glock_dq_uninit(&q_gh);
out:
	qd_put(qd);
	return error;
}

/* GFS2 only supports a subset of the XFS fields */
#define GFS2_FIELDMASK (FS_DQ_BSOFT|FS_DQ_BHARD|FS_DQ_BCOUNT)

static int gfs2_set_dqblk(struct super_block *sb, struct kqid qid,
			  struct fs_disk_quota *fdq)
{
	struct gfs2_sbd *sdp = sb->s_fs_info;
	struct gfs2_inode *ip = GFS2_I(sdp->sd_quota_inode);
	struct gfs2_quota_data *qd;
	struct gfs2_holder q_gh, i_gh;
	unsigned int data_blocks, ind_blocks;
	unsigned int blocks = 0;
	int alloc_required;
	loff_t offset;
	int error;
	int type;

	if (sdp->sd_args.ar_quota == GFS2_QUOTA_OFF)
		return -ESRCH; /* Crazy XFS error code */

	switch(qid.type) {
	case USRQUOTA:
		type = QUOTA_USER;
		if (fdq->d_flags != FS_USER_QUOTA)
			return -EINVAL;
		break;
	case GRPQUOTA:
		type = QUOTA_GROUP;
		if (fdq->d_flags != FS_GROUP_QUOTA)
			return -EINVAL;
		break;
	default:
		return -EINVAL;
	}

	if (fdq->d_fieldmask & ~GFS2_FIELDMASK)
		return -EINVAL;
	if (fdq->d_id != from_kqid(&init_user_ns, qid))
		return -EINVAL;

	error = qd_get(sdp, type, from_kqid(&init_user_ns, qid), &qd);
	if (error)
		return error;

	error = gfs2_rs_alloc(ip);
	if (error)
		goto out_put;

	mutex_lock(&ip->i_inode.i_mutex);
	error = gfs2_glock_nq_init(qd->qd_gl, LM_ST_EXCLUSIVE, 0, &q_gh);
	if (error)
		goto out_unlockput;
	error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &i_gh);
	if (error)
		goto out_q;

	/* Check for existing entry, if none then alloc new blocks */
	error = update_qd(sdp, qd);
	if (error)
		goto out_i;

	/* If nothing has changed, this is a no-op */
	if ((fdq->d_fieldmask & FS_DQ_BSOFT) &&
	    ((fdq->d_blk_softlimit >> sdp->sd_fsb2bb_shift) == be64_to_cpu(qd->qd_qb.qb_warn)))
		fdq->d_fieldmask ^= FS_DQ_BSOFT;

	if ((fdq->d_fieldmask & FS_DQ_BHARD) &&
	    ((fdq->d_blk_hardlimit >> sdp->sd_fsb2bb_shift) == be64_to_cpu(qd->qd_qb.qb_limit)))
		fdq->d_fieldmask ^= FS_DQ_BHARD;

	if ((fdq->d_fieldmask & FS_DQ_BCOUNT) &&
	    ((fdq->d_bcount >> sdp->sd_fsb2bb_shift) == be64_to_cpu(qd->qd_qb.qb_value)))
		fdq->d_fieldmask ^= FS_DQ_BCOUNT;

	if (fdq->d_fieldmask == 0)
		goto out_i;

	offset = qd2offset(qd);
	alloc_required = gfs2_write_alloc_required(ip, offset, sizeof(struct gfs2_quota));
	if (gfs2_is_stuffed(ip))
		alloc_required = 1;
	if (alloc_required) {
		gfs2_write_calc_reserv(ip, sizeof(struct gfs2_quota),
				       &data_blocks, &ind_blocks);
		blocks = 1 + data_blocks + ind_blocks;
		error = gfs2_inplace_reserve(ip, blocks);
		if (error)
			goto out_i;
		blocks += gfs2_rg_blocks(ip, blocks);
	}

	/* Some quotas span block boundaries and can update two blocks,
	   adding an extra block to the transaction to handle such quotas */
	error = gfs2_trans_begin(sdp, blocks + RES_DINODE + 2, 0);
	if (error)
		goto out_release;

	/* Apply changes */
	error = gfs2_adjust_quota(ip, offset, 0, qd, fdq);

	gfs2_trans_end(sdp);
out_release:
	if (alloc_required)
		gfs2_inplace_release(ip);
out_i:
	gfs2_glock_dq_uninit(&i_gh);
out_q:
	gfs2_glock_dq_uninit(&q_gh);
out_unlockput:
	mutex_unlock(&ip->i_inode.i_mutex);
out_put:
	qd_put(qd);
	return error;
}

const struct quotactl_ops gfs2_quotactl_ops = {
	.quota_sync     = gfs2_quota_sync,
	.get_xstate     = gfs2_quota_get_xstate,
	.get_dqblk	= gfs2_get_dqblk,
	.set_dqblk	= gfs2_set_dqblk,
};