Linux 4.19-rc7

[linux-2.6/btrfs-unstable.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.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#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 <linux/lockref.h>
#include <linux/list_lru.h>
#include <linux/rcupdate.h>
#include <linux/rculist_bl.h>
#include <linux/bit_spinlock.h>
#include <linux/jhash.h>
#include <linux/vmalloc.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 GFS2_QD_HASH_SHIFT      12
#define GFS2_QD_HASH_SIZE       BIT(GFS2_QD_HASH_SHIFT)
#define GFS2_QD_HASH_MASK       (GFS2_QD_HASH_SIZE - 1)

/* Lock order: qd_lock -> bucket lock -> qd->lockref.lock -> lru lock */
/*                     -> sd_bitmap_lock                              */
static DEFINE_SPINLOCK(qd_lock);
struct list_lru gfs2_qd_lru;

static struct hlist_bl_head qd_hash_table[GFS2_QD_HASH_SIZE];

static unsigned int gfs2_qd_hash(const struct gfs2_sbd *sdp,
                                 const struct kqid qid)
{
        unsigned int h;

        h = jhash(&sdp, sizeof(struct gfs2_sbd *), 0);
        h = jhash(&qid, sizeof(struct kqid), h);

        return h & GFS2_QD_HASH_MASK;
}

static inline void spin_lock_bucket(unsigned int hash)
{
        hlist_bl_lock(&qd_hash_table[hash]);
}

static inline void spin_unlock_bucket(unsigned int hash)
{
        hlist_bl_unlock(&qd_hash_table[hash]);
}

static void gfs2_qd_dealloc(struct rcu_head *rcu)
{
        struct gfs2_quota_data *qd = container_of(rcu, struct gfs2_quota_data, qd_rcu);
        kmem_cache_free(gfs2_quotad_cachep, qd);
}

static void gfs2_qd_dispose(struct list_head *list)
{
        struct gfs2_quota_data *qd;
        struct gfs2_sbd *sdp;

        while (!list_empty(list)) {
                qd = list_entry(list->next, struct gfs2_quota_data, qd_lru);
                sdp = qd->qd_gl->gl_name.ln_sbd;

                list_del(&qd->qd_lru);

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

                spin_lock_bucket(qd->qd_hash);
                hlist_bl_del_rcu(&qd->qd_hlist);
                spin_unlock_bucket(qd->qd_hash);

                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 */
                call_rcu(&qd->qd_rcu, gfs2_qd_dealloc);
        }
}


static enum lru_status gfs2_qd_isolate(struct list_head *item,
                struct list_lru_one *lru, spinlock_t *lru_lock, void *arg)
{
        struct list_head *dispose = arg;
        struct gfs2_quota_data *qd = list_entry(item, struct gfs2_quota_data, qd_lru);

        if (!spin_trylock(&qd->qd_lockref.lock))
                return LRU_SKIP;

        if (qd->qd_lockref.count == 0) {
                lockref_mark_dead(&qd->qd_lockref);
                list_lru_isolate_move(lru, &qd->qd_lru, dispose);
        }

        spin_unlock(&qd->qd_lockref.lock);
        return LRU_REMOVED;
}

static unsigned long gfs2_qd_shrink_scan(struct shrinker *shrink,
                                         struct shrink_control *sc)
{
        LIST_HEAD(dispose);
        unsigned long freed;

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

        freed = list_lru_shrink_walk(&gfs2_qd_lru, sc,
                                     gfs2_qd_isolate, &dispose);

        gfs2_qd_dispose(&dispose);

        return freed;
}

static unsigned long gfs2_qd_shrink_count(struct shrinker *shrink,
                                          struct shrink_control *sc)
{
        return vfs_pressure_ratio(list_lru_shrink_count(&gfs2_qd_lru, sc));
}

struct shrinker gfs2_qd_shrinker = {
        .count_objects = gfs2_qd_shrink_count,
        .scan_objects = gfs2_qd_shrink_scan,
        .seeks = DEFAULT_SEEKS,
        .flags = SHRINKER_NUMA_AWARE,
};


static u64 qd2index(struct gfs2_quota_data *qd)
{
        struct kqid qid = qd->qd_id;
        return (2 * (u64)from_kqid(&init_user_ns, qid)) +
                ((qid.type == USRQUOTA) ? 0 : 1);
}

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

        offset = qd2index(qd);
        offset *= sizeof(struct gfs2_quota);

        return offset;
}

static struct gfs2_quota_data *qd_alloc(unsigned hash, struct gfs2_sbd *sdp, struct kqid qid)
{
        struct gfs2_quota_data *qd;
        int error;

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

        qd->qd_sbd = sdp;
        qd->qd_lockref.count = 1;
        spin_lock_init(&qd->qd_lockref.lock);
        qd->qd_id = qid;
        qd->qd_slot = -1;
        INIT_LIST_HEAD(&qd->qd_lru);
        qd->qd_hash = hash;

        error = gfs2_glock_get(sdp, qd2index(qd),
                              &gfs2_quota_glops, CREATE, &qd->qd_gl);
        if (error)
                goto fail;

        return qd;

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

static struct gfs2_quota_data *gfs2_qd_search_bucket(unsigned int hash,
                                                     const struct gfs2_sbd *sdp,
                                                     struct kqid qid)
{
        struct gfs2_quota_data *qd;
        struct hlist_bl_node *h;

        hlist_bl_for_each_entry_rcu(qd, h, &qd_hash_table[hash], qd_hlist) {
                if (!qid_eq(qd->qd_id, qid))
                        continue;
                if (qd->qd_sbd != sdp)
                        continue;
                if (lockref_get_not_dead(&qd->qd_lockref)) {
                        list_lru_del(&gfs2_qd_lru, &qd->qd_lru);
                        return qd;
                }
        }

        return NULL;
}


static int qd_get(struct gfs2_sbd *sdp, struct kqid qid,
                  struct gfs2_quota_data **qdp)
{
        struct gfs2_quota_data *qd, *new_qd;
        unsigned int hash = gfs2_qd_hash(sdp, qid);

        rcu_read_lock();
        *qdp = qd = gfs2_qd_search_bucket(hash, sdp, qid);
        rcu_read_unlock();

        if (qd)
                return 0;

        new_qd = qd_alloc(hash, sdp, qid);
        if (!new_qd)
                return -ENOMEM;

        spin_lock(&qd_lock);
        spin_lock_bucket(hash);
        *qdp = qd = gfs2_qd_search_bucket(hash, sdp, qid);
        if (qd == NULL) {
                *qdp = new_qd;
                list_add(&new_qd->qd_list, &sdp->sd_quota_list);
                hlist_bl_add_head_rcu(&new_qd->qd_hlist, &qd_hash_table[hash]);
                atomic_inc(&sdp->sd_quota_count);
        }
        spin_unlock_bucket(hash);
        spin_unlock(&qd_lock);

        if (qd) {
                gfs2_glock_put(new_qd->qd_gl);
                kmem_cache_free(gfs2_quotad_cachep, new_qd);
        }

        return 0;
}


static void qd_hold(struct gfs2_quota_data *qd)
{
        struct gfs2_sbd *sdp = qd->qd_gl->gl_name.ln_sbd;
        gfs2_assert(sdp, !__lockref_is_dead(&qd->qd_lockref));
        lockref_get(&qd->qd_lockref);
}

static void qd_put(struct gfs2_quota_data *qd)
{
        if (lockref_put_or_lock(&qd->qd_lockref))
                return;

        qd->qd_lockref.count = 0;
        list_lru_add(&gfs2_qd_lru, &qd->qd_lru);
        spin_unlock(&qd->qd_lockref.lock);

}

static int slot_get(struct gfs2_quota_data *qd)
{
        struct gfs2_sbd *sdp = qd->qd_sbd;
        unsigned int bit;
        int error = 0;

        spin_lock(&sdp->sd_bitmap_lock);
        if (qd->qd_slot_count != 0)
                goto out;

        error = -ENOSPC;
        bit = find_first_zero_bit(sdp->sd_quota_bitmap, sdp->sd_quota_slots);
        if (bit < sdp->sd_quota_slots) {
                set_bit(bit, sdp->sd_quota_bitmap);
                qd->qd_slot = bit;
                error = 0;
out:
                qd->qd_slot_count++;
        }
        spin_unlock(&sdp->sd_bitmap_lock);

        return error;
}

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

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

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

        spin_lock(&sdp->sd_bitmap_lock);
        gfs2_assert(sdp, qd->qd_slot_count);
        if (!--qd->qd_slot_count) {
                BUG_ON(!test_and_clear_bit(qd->qd_slot, sdp->sd_quota_bitmap));
                qd->qd_slot = -1;
        }
        spin_unlock(&sdp->sd_bitmap_lock);
}

static int bh_get(struct gfs2_quota_data *qd)
{
        struct gfs2_sbd *sdp = qd->qd_gl->gl_name.ln_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 = BIT(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, 0, &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_name.ln_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_check_sync(struct gfs2_sbd *sdp, struct gfs2_quota_data *qd,
                         u64 *sync_gen)
{
        if (test_bit(QDF_LOCKED, &qd->qd_flags) ||
            !test_bit(QDF_CHANGE, &qd->qd_flags) ||
            (sync_gen && (qd->qd_sync_gen >= *sync_gen)))
                return 0;

        if (!lockref_get_not_dead(&qd->qd_lockref))
                return 0;

        list_move_tail(&qd->qd_list, &sdp->sd_quota_list);
        set_bit(QDF_LOCKED, &qd->qd_flags);
        qd->qd_change_sync = qd->qd_change;
        slot_hold(qd);
        return 1;
}

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 (sb_rdonly(sdp->sd_vfs))
                return 0;

        spin_lock(&qd_lock);

        list_for_each_entry(qd, &sdp->sd_quota_list, qd_list) {
                found = qd_check_sync(sdp, qd, &sdp->sd_quota_sync_gen);
                if (found)
                        break;
        }

        if (!found)
                qd = NULL;

        spin_unlock(&qd_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 void qd_unlock(struct gfs2_quota_data *qd)
{
        gfs2_assert_warn(qd->qd_gl->gl_name.ln_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, struct kqid qid,
                    struct gfs2_quota_data **qdp)
{
        int error;

        error = qd_get(sdp, qid, 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);
}

/**
 * gfs2_qa_alloc - make sure we have a quota allocations data structure,
 *                 if necessary
 * @ip: the inode for this reservation
 */
int gfs2_qa_alloc(struct gfs2_inode *ip)
{
        int error = 0;
        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);

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

        down_write(&ip->i_rw_mutex);
        if (ip->i_qadata == NULL) {
                ip->i_qadata = kmem_cache_zalloc(gfs2_qadata_cachep, GFP_NOFS);
                if (!ip->i_qadata)
                        error = -ENOMEM;
        }
        up_write(&ip->i_rw_mutex);
        return error;
}

void gfs2_qa_delete(struct gfs2_inode *ip, atomic_t *wcount)
{
        down_write(&ip->i_rw_mutex);
        if (ip->i_qadata && ((wcount == NULL) || (atomic_read(wcount) <= 1))) {
                kmem_cache_free(gfs2_qadata_cachep, ip->i_qadata);
                ip->i_qadata = NULL;
        }
        up_write(&ip->i_rw_mutex);
}

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

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

        if (ip->i_qadata == NULL) {
                error = gfs2_rsqa_alloc(ip);
                if (error)
                        return error;
        }

        qd = ip->i_qadata->qa_qd;

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

        error = qdsb_get(sdp, make_kqid_uid(ip->i_inode.i_uid), qd);
        if (error)
                goto out;
        ip->i_qadata->qa_qd_num++;
        qd++;

        error = qdsb_get(sdp, make_kqid_gid(ip->i_inode.i_gid), qd);
        if (error)
                goto out;
        ip->i_qadata->qa_qd_num++;
        qd++;

        if (!uid_eq(uid, NO_UID_QUOTA_CHANGE) &&
            !uid_eq(uid, ip->i_inode.i_uid)) {
                error = qdsb_get(sdp, make_kqid_uid(uid), qd);
                if (error)
                        goto out;
                ip->i_qadata->qa_qd_num++;
                qd++;
        }

        if (!gid_eq(gid, NO_GID_QUOTA_CHANGE) &&
            !gid_eq(gid, ip->i_inode.i_gid)) {
                error = qdsb_get(sdp, make_kqid_gid(gid), qd);
                if (error)
                        goto out;
                ip->i_qadata->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);
        u32 x;

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

        for (x = 0; x < ip->i_qadata->qa_qd_num; x++) {
                qdsb_put(ip->i_qadata->qa_qd[x]);
                ip->i_qadata->qa_qd[x] = NULL;
        }
        ip->i_qadata->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 (qid_lt(qd_a->qd_id, qd_b->qd_id))
                return -1;
        if (qid_lt(qd_b->qd_id, qd_a->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_name.ln_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_meta(ip->i_gl, qd->qd_bh);

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

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

        spin_lock(&qd_lock);
        qd->qd_change = x;
        spin_unlock(&qd_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);
        }

        if (change < 0) /* Reset quiet flag if we freed some blocks */
                clear_bit(QDF_QMSG_QUIET, &qd->qd_flags);
        mutex_unlock(&sdp->sd_quota_mutex);
}

static int gfs2_write_buf_to_page(struct gfs2_inode *ip, unsigned long index,
                                  unsigned off, void *buf, unsigned bytes)
{
        struct inode *inode = &ip->i_inode;
        struct gfs2_sbd *sdp = GFS2_SB(inode);
        struct address_space *mapping = inode->i_mapping;
        struct page *page;
        struct buffer_head *bh;
        void *kaddr;
        u64 blk;
        unsigned bsize = sdp->sd_sb.sb_bsize, bnum = 0, boff = 0;
        unsigned to_write = bytes, pg_off = off;
        int done = 0;

        blk = index << (PAGE_SHIFT - sdp->sd_sb.sb_bsize_shift);
        boff = off % bsize;

        page = find_or_create_page(mapping, index, GFP_NOFS);
        if (!page)
                return -ENOMEM;
        if (!page_has_buffers(page))
                create_empty_buffers(page, bsize, 0);

        bh = page_buffers(page);
        while (!done) {
                /* Find the beginning block within the page */
                if (pg_off >= ((bnum * bsize) + bsize)) {
                        bh = bh->b_this_page;
                        bnum++;
                        blk++;
                        continue;
                }
                if (!buffer_mapped(bh)) {
                        gfs2_block_map(inode, blk, bh, 1);
                        if (!buffer_mapped(bh))
                                goto unlock_out;
                        /* If it's a newly allocated disk block, zero it */
                        if (buffer_new(bh))
                                zero_user(page, bnum * bsize, bh->b_size);
                }
                if (PageUptodate(page))
                        set_buffer_uptodate(bh);
                if (!buffer_uptodate(bh)) {
                        ll_rw_block(REQ_OP_READ, REQ_META | REQ_PRIO, 1, &bh);
                        wait_on_buffer(bh);
                        if (!buffer_uptodate(bh))
                                goto unlock_out;
                }
                if (gfs2_is_jdata(ip))
                        gfs2_trans_add_data(ip->i_gl, bh);
                else
                        gfs2_ordered_add_inode(ip);

                /* If we need to write to the next block as well */
                if (to_write > (bsize - boff)) {
                        pg_off += (bsize - boff);
                        to_write -= (bsize - boff);
                        boff = pg_off % bsize;
                        continue;
                }
                done = 1;
        }

        /* Write to the page, now that we have setup the buffer(s) */
        kaddr = kmap_atomic(page);
        memcpy(kaddr + off, buf, bytes);
        flush_dcache_page(page);
        kunmap_atomic(kaddr);
        unlock_page(page);
        put_page(page);

        return 0;

unlock_out:
        unlock_page(page);
        put_page(page);
        return -EIO;
}

static int gfs2_write_disk_quota(struct gfs2_inode *ip, struct gfs2_quota *qp,
                                 loff_t loc)
{
        unsigned long pg_beg;
        unsigned pg_off, nbytes, overflow = 0;
        int pg_oflow = 0, error;
        void *ptr;

        nbytes = sizeof(struct gfs2_quota);

        pg_beg = loc >> PAGE_SHIFT;
        pg_off = loc % PAGE_SIZE;

        /* If the quota straddles a page boundary, split the write in two */
        if ((pg_off + nbytes) > PAGE_SIZE) {
                pg_oflow = 1;
                overflow = (pg_off + nbytes) - PAGE_SIZE;
        }

        ptr = qp;
        error = gfs2_write_buf_to_page(ip, pg_beg, pg_off, ptr,
                                       nbytes - overflow);
        /* If there's an overflow, write the remaining bytes to the next page */
        if (!error && pg_oflow)
                error = gfs2_write_buf_to_page(ip, pg_beg + 1, 0,
                                               ptr + nbytes - overflow,
                                               overflow);
        return error;
}

/**
 * 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 qc_dqblk *fdq)
{
        struct inode *inode = &ip->i_inode;
        struct gfs2_sbd *sdp = GFS2_SB(inode);
        struct gfs2_quota q;
        int err;
        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;

        loc -= sizeof(q); /* gfs2_internal_read would've advanced the loc ptr */
        err = -EIO;
        be64_add_cpu(&q.qu_value, change);
        if (((s64)be64_to_cpu(q.qu_value)) < 0)
                q.qu_value = 0; /* Never go negative on quota usage */
        qd->qd_qb.qb_value = q.qu_value;
        if (fdq) {
                if (fdq->d_fieldmask & QC_SPC_SOFT) {
                        q.qu_warn = cpu_to_be64(fdq->d_spc_softlimit >> sdp->sd_sb.sb_bsize_shift);
                        qd->qd_qb.qb_warn = q.qu_warn;
                }
                if (fdq->d_fieldmask & QC_SPC_HARD) {
                        q.qu_limit = cpu_to_be64(fdq->d_spc_hardlimit >> sdp->sd_sb.sb_bsize_shift);
                        qd->qd_qb.qb_limit = q.qu_limit;
                }
                if (fdq->d_fieldmask & QC_SPACE) {
                        q.qu_value = cpu_to_be64(fdq->d_space >> sdp->sd_sb.sb_bsize_shift);
                        qd->qd_qb.qb_value = q.qu_value;
                }
        }

        err = gfs2_write_disk_quota(ip, &q, loc);
        if (!err) {
                size = loc + sizeof(struct gfs2_quota);
                if (size > inode->i_size)
                        i_size_write(inode, size);
                inode->i_mtime = inode->i_atime = current_time(inode);
                mark_inode_dirty(inode);
                set_bit(QDF_REFRESH, &qd->qd_flags);
        }

        return err;
}

static int do_sync(unsigned int num_qd, struct gfs2_quota_data **qda)
{
        struct gfs2_sbd *sdp = (*qda)->qd_gl->gl_name.ln_sbd;
        struct gfs2_inode *ip = GFS2_I(sdp->sd_quota_inode);
        struct gfs2_alloc_parms ap = { .aflags = 0, };
        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_rsqa_alloc(ip);
        if (error)
                return error;

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

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

        sort(qda, num_qd, sizeof(struct gfs2_quota_data *), sort_qd, NULL);
        inode_lock(&ip->i_inode);
        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));
        ap.target = reserved;
        error = gfs2_inplace_reserve(ip, &ap);
        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]);
        inode_unlock(&ip->i_inode);
        kfree(ghs);
        gfs2_log_flush(ip->i_gl->gl_name.ln_sbd, ip->i_gl,
                       GFS2_LOG_HEAD_FLUSH_NORMAL | GFS2_LFC_DO_SYNC);
        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_lksb.sb_lvbptr;
        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_name.ln_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;

        if (test_and_clear_bit(QDF_REFRESH, &qd->qd_flags))
                force_refresh = FORCE;

        qd->qd_qb = *(struct gfs2_quota_lvb *)qd->qd_gl->gl_lksb.sb_lvbptr;

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

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

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

        sort(ip->i_qadata->qa_qd, ip->i_qadata->qa_qd_num,
             sizeof(struct gfs2_quota_data *), sort_qd, NULL);

        for (x = 0; x < ip->i_qadata->qa_qd_num; x++) {
                qd = ip->i_qadata->qa_qd[x];
                error = do_glock(qd, NO_FORCE, &ip->i_qadata->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_qadata->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_name.ln_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_lock);
        value = qd->qd_change;
        spin_unlock(&qd_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_sbd *sdp = GFS2_SB(&ip->i_inode);
        struct gfs2_quota_data *qda[4];
        unsigned int count = 0;
        u32 x;
        int found;

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

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

                qd = ip->i_qadata->qa_qd[x];
                sync = need_sync(qd);

                gfs2_glock_dq_uninit(&ip->i_qadata->qa_qd_ghs[x]);
                if (!sync)
                        continue;

                spin_lock(&qd_lock);
                found = qd_check_sync(sdp, qd, NULL);
                spin_unlock(&qd_lock);

                if (!found)
                        continue;

                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);
                        continue;
                }

                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_name.ln_sbd;

        fs_info(sdp, "quota %s for %s %u\n",
                type,
                (qd->qd_id.type == USRQUOTA) ? "user" : "group",
                from_kqid(&init_user_ns, qd->qd_id));

        return 0;
}

/**
 * gfs2_quota_check - check if allocating new blocks will exceed quota
 * @ip:  The inode for which this check is being performed
 * @uid: The uid to check against
 * @gid: The gid to check against
 * @ap:  The allocation parameters. ap->target contains the requested
 *       blocks. ap->min_target, if set, contains the minimum blks
 *       requested.
 *
 * Returns: 0 on success.
 *                  min_req = ap->min_target ? ap->min_target : ap->target;
 *                  quota must allow atleast min_req blks for success and
 *                  ap->allowed is set to the number of blocks allowed
 *
 *          -EDQUOT otherwise, quota violation. ap->allowed is set to number
 *                  of blocks available.
 */
int gfs2_quota_check(struct gfs2_inode *ip, kuid_t uid, kgid_t gid,
                     struct gfs2_alloc_parms *ap)
{
        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
        struct gfs2_quota_data *qd;
        s64 value, warn, limit;
        u32 x;
        int error = 0;

        ap->allowed = UINT_MAX; /* Assume we are permitted a whole lot */
        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_qadata->qa_qd_num; x++) {
                qd = ip->i_qadata->qa_qd[x];

                if (!(qid_eq(qd->qd_id, make_kqid_uid(uid)) ||
                      qid_eq(qd->qd_id, make_kqid_gid(gid))))
                        continue;

                warn = (s64)be64_to_cpu(qd->qd_qb.qb_warn);
                limit = (s64)be64_to_cpu(qd->qd_qb.qb_limit);
                value = (s64)be64_to_cpu(qd->qd_qb.qb_value);
                spin_lock(&qd_lock);
                value += qd->qd_change;
                spin_unlock(&qd_lock);

                if (limit > 0 && (limit - value) < ap->allowed)
                        ap->allowed = limit - value;
                /* If we can't meet the target */
                if (limit && limit < (value + (s64)ap->target)) {
                        /* If no min_target specified or we don't meet
                         * min_target, return -EDQUOT */
                        if (!ap->min_target || ap->min_target > ap->allowed) {
                                if (!test_and_set_bit(QDF_QMSG_QUIET,
                                                      &qd->qd_flags)) {
                                        print_message(qd, "exceeded");
                                        quota_send_warning(qd->qd_id,
                                                           sdp->sd_vfs->s_dev,
                                                           QUOTA_NL_BHARDWARN);
                                }
                                error = -EDQUOT;
                                break;
                        }
                } else if (warn && warn < value &&
                           time_after_eq(jiffies, qd->qd_last_warn +
                                         gfs2_tune_get(sdp, gt_quota_warn_period)
                                         * HZ)) {
                        quota_send_warning(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,
                       kuid_t uid, kgid_t gid)
{
        struct gfs2_quota_data *qd;
        u32 x;
        struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);

        if (sdp->sd_args.ar_quota != GFS2_QUOTA_ON ||
            gfs2_assert_warn(sdp, change))
                return;
        if (ip->i_diskflags & GFS2_DIF_SYSTEM)
                return;

        for (x = 0; x < ip->i_qadata->qa_qd_num; x++) {
                qd = ip->i_qadata->qa_qd[x];

                if (qid_eq(qd->qd_id, make_kqid_uid(uid)) ||
                    qid_eq(qd->qd_id, make_kqid_gid(gid))) {
                        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 = PAGE_SIZE/sizeof(struct gfs2_holder);
        unsigned int num_qd;
        unsigned int x;
        int error = 0;

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

        mutex_lock(&sdp->sd_quota_sync_mutex);
        sdp->sd_quota_sync_gen++;

        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);

        mutex_unlock(&sdp->sd_quota_sync_mutex);
        kfree(qda);

        return error;
}

int gfs2_quota_refresh(struct gfs2_sbd *sdp, struct kqid qid)
{
        struct gfs2_quota_data *qd;
        struct gfs2_holder q_gh;
        int error;

        error = qd_get(sdp, qid, &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;
}

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;
        unsigned int hash;
        unsigned int bm_size;
        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;
        bm_size = DIV_ROUND_UP(sdp->sd_quota_slots, 8 * sizeof(unsigned long));
        bm_size *= sizeof(unsigned long);
        error = -ENOMEM;
        sdp->sd_quota_bitmap = kzalloc(bm_size, GFP_NOFS | __GFP_NOWARN);
        if (sdp->sd_quota_bitmap == NULL)
                sdp->sd_quota_bitmap = __vmalloc(bm_size, GFP_NOFS |
                                                 __GFP_ZERO, PAGE_KERNEL);
        if (!sdp->sd_quota_bitmap)
                return error;

        for (x = 0; x < blocks; x++) {
                struct buffer_head *bh;
                const struct gfs2_quota_change *qc;
                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;
                }

                qc = (const struct gfs2_quota_change *)(bh->b_data + sizeof(struct gfs2_meta_header));
                for (y = 0; y < sdp->sd_qc_per_block && slot < sdp->sd_quota_slots;
                     y++, slot++) {
                        struct gfs2_quota_data *qd;
                        s64 qc_change = be64_to_cpu(qc->qc_change);
                        u32 qc_flags = be32_to_cpu(qc->qc_flags);
                        enum quota_type qtype = (qc_flags & GFS2_QCF_USER) ?
                                                USRQUOTA : GRPQUOTA;
                        struct kqid qc_id = make_kqid(&init_user_ns, qtype,
                                                      be32_to_cpu(qc->qc_id));
                        qc++;
                        if (!qc_change)
                                continue;

                        hash = gfs2_qd_hash(sdp, qc_id);
                        qd = qd_alloc(hash, sdp, qc_id);
                        if (qd == NULL) {
                                brelse(bh);
                                goto fail;
                        }

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

                        spin_lock(&qd_lock);
                        BUG_ON(test_and_set_bit(slot, sdp->sd_quota_bitmap));
                        list_add(&qd->qd_list, &sdp->sd_quota_list);
                        atomic_inc(&sdp->sd_quota_count);
                        spin_unlock(&qd_lock);

                        spin_lock_bucket(hash);
                        hlist_bl_add_head_rcu(&qd->qd_hlist, &qd_hash_table[hash]);
                        spin_unlock_bucket(hash);

                        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;

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

                list_del(&qd->qd_list);

                /* Also remove if this qd exists in the reclaim list */
                list_lru_del(&gfs2_qd_lru, &qd->qd_lru);
                atomic_dec(&sdp->sd_quota_count);
                spin_unlock(&qd_lock);

                spin_lock_bucket(qd->qd_hash);
                hlist_bl_del_rcu(&qd->qd_hlist);
                spin_unlock_bucket(qd->qd_hash);

                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);
                call_rcu(&qd->qd_rcu, gfs2_qd_dealloc);

                spin_lock(&qd_lock);
        }
        spin_unlock(&qd_lock);

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

        kvfree(sdp->sd_quota_bitmap);
        sdp->sd_quota_bitmap = NULL;
}

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);
                sdp->sd_log_error = error;
                wake_up(&sdp->sd_logd_waitq);
        }
}

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, 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_state(struct super_block *sb, struct qc_state *state)
{
        struct gfs2_sbd *sdp = sb->s_fs_info;

        memset(state, 0, sizeof(*state));

        switch (sdp->sd_args.ar_quota) {
        case GFS2_QUOTA_ON:
                state->s_state[USRQUOTA].flags |= QCI_LIMITS_ENFORCED;
                state->s_state[GRPQUOTA].flags |= QCI_LIMITS_ENFORCED;
                /*FALLTHRU*/
        case GFS2_QUOTA_ACCOUNT:
                state->s_state[USRQUOTA].flags |= QCI_ACCT_ENABLED |
                                                  QCI_SYSFILE;
                state->s_state[GRPQUOTA].flags |= QCI_ACCT_ENABLED |
                                                  QCI_SYSFILE;
                break;
        case GFS2_QUOTA_OFF:
                break;
        }
        if (sdp->sd_quota_inode) {
                state->s_state[USRQUOTA].ino =
                                        GFS2_I(sdp->sd_quota_inode)->i_no_addr;
                state->s_state[USRQUOTA].blocks = sdp->sd_quota_inode->i_blocks;
        }
        state->s_state[USRQUOTA].nextents = 1;  /* unsupported */
        state->s_state[GRPQUOTA] = state->s_state[USRQUOTA];
        state->s_incoredqs = list_lru_count(&gfs2_qd_lru);
        return 0;
}

static int gfs2_get_dqblk(struct super_block *sb, struct kqid qid,
                          struct qc_dqblk *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;

        memset(fdq, 0, sizeof(*fdq));

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

        if ((qid.type != USRQUOTA) &&
            (qid.type != GRPQUOTA))
                return -EINVAL;

        error = qd_get(sdp, 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_lksb.sb_lvbptr;
        fdq->d_spc_hardlimit = be64_to_cpu(qlvb->qb_limit) << sdp->sd_sb.sb_bsize_shift;
        fdq->d_spc_softlimit = be64_to_cpu(qlvb->qb_warn) << sdp->sd_sb.sb_bsize_shift;
        fdq->d_space = be64_to_cpu(qlvb->qb_value) << sdp->sd_sb.sb_bsize_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 (QC_SPC_SOFT|QC_SPC_HARD|QC_SPACE)

static int gfs2_set_dqblk(struct super_block *sb, struct kqid qid,
                          struct qc_dqblk *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;

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

        if ((qid.type != USRQUOTA) &&
            (qid.type != GRPQUOTA))
                return -EINVAL;

        if (fdq->d_fieldmask & ~GFS2_FIELDMASK)
                return -EINVAL;

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

        error = gfs2_rsqa_alloc(ip);
        if (error)
                goto out_put;

        inode_lock(&ip->i_inode);
        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 & QC_SPC_SOFT) &&
            ((fdq->d_spc_softlimit >> sdp->sd_sb.sb_bsize_shift) == be64_to_cpu(qd->qd_qb.qb_warn)))
                fdq->d_fieldmask ^= QC_SPC_SOFT;

        if ((fdq->d_fieldmask & QC_SPC_HARD) &&
            ((fdq->d_spc_hardlimit >> sdp->sd_sb.sb_bsize_shift) == be64_to_cpu(qd->qd_qb.qb_limit)))
                fdq->d_fieldmask ^= QC_SPC_HARD;

        if ((fdq->d_fieldmask & QC_SPACE) &&
            ((fdq->d_space >> sdp->sd_sb.sb_bsize_shift) == be64_to_cpu(qd->qd_qb.qb_value)))
                fdq->d_fieldmask ^= QC_SPACE;

        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) {
                struct gfs2_alloc_parms ap = { .aflags = 0, };
                gfs2_write_calc_reserv(ip, sizeof(struct gfs2_quota),
                                       &data_blocks, &ind_blocks);
                blocks = 1 + data_blocks + ind_blocks;
                ap.target = blocks;
                error = gfs2_inplace_reserve(ip, &ap);
                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);
        if (!error)
                clear_bit(QDF_QMSG_QUIET, &qd->qd_flags);

        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:
        inode_unlock(&ip->i_inode);
out_put:
        qd_put(qd);
        return error;
}

const struct quotactl_ops gfs2_quotactl_ops = {
        .quota_sync     = gfs2_quota_sync,
        .get_state      = gfs2_quota_get_state,
        .get_dqblk      = gfs2_get_dqblk,
        .set_dqblk      = gfs2_set_dqblk,
};

void __init gfs2_quota_hash_init(void)
{
        unsigned i;

        for(i = 0; i < GFS2_QD_HASH_SIZE; i++)
                INIT_HLIST_BL_HEAD(&qd_hash_table[i]);
}