quota.c

Go to the documentation of this file.

/*
 * 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) {
        error = gfs2_rs_alloc(ip);
        if (error)
            return error;
    }

    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);
}

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);
    }
}


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,
};