mm: fix exec activate_mm vs TLB shootdown and lazy tlb switching race

[linux/fpc-iii.git] / fs / ocfs2 / quota_global.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  Implementation of operations over global quota file
 */
#include <linux/spinlock.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/quota.h>
#include <linux/quotaops.h>
#include <linux/dqblk_qtree.h>
#include <linux/jiffies.h>
#include <linux/writeback.h>
#include <linux/workqueue.h>
#include <linux/llist.h>

#include <cluster/masklog.h>

#include "ocfs2_fs.h"
#include "ocfs2.h"
#include "alloc.h"
#include "blockcheck.h"
#include "inode.h"
#include "journal.h"
#include "file.h"
#include "sysfile.h"
#include "dlmglue.h"
#include "uptodate.h"
#include "super.h"
#include "buffer_head_io.h"
#include "quota.h"
#include "ocfs2_trace.h"

/*
 * Locking of quotas with OCFS2 is rather complex. Here are rules that
 * should be obeyed by all the functions:
 * - any write of quota structure (either to local or global file) is protected
 *   by dqio_sem or dquot->dq_lock.
 * - any modification of global quota file holds inode cluster lock, i_mutex,
 *   and ip_alloc_sem of the global quota file (achieved by
 *   ocfs2_lock_global_qf). It also has to hold qinfo_lock.
 * - an allocation of new blocks for local quota file is protected by
 *   its ip_alloc_sem
 *
 * A rough sketch of locking dependencies (lf = local file, gf = global file):
 * Normal filesystem operation:
 *   start_trans -> dqio_sem -> write to lf
 * Syncing of local and global file:
 *   ocfs2_lock_global_qf -> start_trans -> dqio_sem -> qinfo_lock ->
 *     write to gf
 *                                                     -> write to lf
 * Acquire dquot for the first time:
 *   dq_lock -> ocfs2_lock_global_qf -> qinfo_lock -> read from gf
 *                                   -> alloc space for gf
 *                                   -> start_trans -> qinfo_lock -> write to gf
 *           -> ip_alloc_sem of lf -> alloc space for lf
 *           -> write to lf
 * Release last reference to dquot:
 *   dq_lock -> ocfs2_lock_global_qf -> start_trans -> qinfo_lock -> write to gf
 *           -> write to lf
 * Note that all the above operations also hold the inode cluster lock of lf.
 * Recovery:
 *   inode cluster lock of recovered lf
 *     -> read bitmaps -> ip_alloc_sem of lf
 *     -> ocfs2_lock_global_qf -> start_trans -> dqio_sem -> qinfo_lock ->
 *        write to gf
 */

static void qsync_work_fn(struct work_struct *work);

static void ocfs2_global_disk2memdqb(struct dquot *dquot, void *dp)
{
        struct ocfs2_global_disk_dqblk *d = dp;
        struct mem_dqblk *m = &dquot->dq_dqb;

        /* Update from disk only entries not set by the admin */
        if (!test_bit(DQ_LASTSET_B + QIF_ILIMITS_B, &dquot->dq_flags)) {
                m->dqb_ihardlimit = le64_to_cpu(d->dqb_ihardlimit);
                m->dqb_isoftlimit = le64_to_cpu(d->dqb_isoftlimit);
        }
        if (!test_bit(DQ_LASTSET_B + QIF_INODES_B, &dquot->dq_flags))
                m->dqb_curinodes = le64_to_cpu(d->dqb_curinodes);
        if (!test_bit(DQ_LASTSET_B + QIF_BLIMITS_B, &dquot->dq_flags)) {
                m->dqb_bhardlimit = le64_to_cpu(d->dqb_bhardlimit);
                m->dqb_bsoftlimit = le64_to_cpu(d->dqb_bsoftlimit);
        }
        if (!test_bit(DQ_LASTSET_B + QIF_SPACE_B, &dquot->dq_flags))
                m->dqb_curspace = le64_to_cpu(d->dqb_curspace);
        if (!test_bit(DQ_LASTSET_B + QIF_BTIME_B, &dquot->dq_flags))
                m->dqb_btime = le64_to_cpu(d->dqb_btime);
        if (!test_bit(DQ_LASTSET_B + QIF_ITIME_B, &dquot->dq_flags))
                m->dqb_itime = le64_to_cpu(d->dqb_itime);
        OCFS2_DQUOT(dquot)->dq_use_count = le32_to_cpu(d->dqb_use_count);
}

static void ocfs2_global_mem2diskdqb(void *dp, struct dquot *dquot)
{
        struct ocfs2_global_disk_dqblk *d = dp;
        struct mem_dqblk *m = &dquot->dq_dqb;

        d->dqb_id = cpu_to_le32(from_kqid(&init_user_ns, dquot->dq_id));
        d->dqb_use_count = cpu_to_le32(OCFS2_DQUOT(dquot)->dq_use_count);
        d->dqb_ihardlimit = cpu_to_le64(m->dqb_ihardlimit);
        d->dqb_isoftlimit = cpu_to_le64(m->dqb_isoftlimit);
        d->dqb_curinodes = cpu_to_le64(m->dqb_curinodes);
        d->dqb_bhardlimit = cpu_to_le64(m->dqb_bhardlimit);
        d->dqb_bsoftlimit = cpu_to_le64(m->dqb_bsoftlimit);
        d->dqb_curspace = cpu_to_le64(m->dqb_curspace);
        d->dqb_btime = cpu_to_le64(m->dqb_btime);
        d->dqb_itime = cpu_to_le64(m->dqb_itime);
        d->dqb_pad1 = d->dqb_pad2 = 0;
}

static int ocfs2_global_is_id(void *dp, struct dquot *dquot)
{
        struct ocfs2_global_disk_dqblk *d = dp;
        struct ocfs2_mem_dqinfo *oinfo =
                        sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv;

        if (qtree_entry_unused(&oinfo->dqi_gi, dp))
                return 0;

        return qid_eq(make_kqid(&init_user_ns, dquot->dq_id.type,
                                le32_to_cpu(d->dqb_id)),
                      dquot->dq_id);
}

const struct qtree_fmt_operations ocfs2_global_ops = {
        .mem2disk_dqblk = ocfs2_global_mem2diskdqb,
        .disk2mem_dqblk = ocfs2_global_disk2memdqb,
        .is_id = ocfs2_global_is_id,
};

int ocfs2_validate_quota_block(struct super_block *sb, struct buffer_head *bh)
{
        struct ocfs2_disk_dqtrailer *dqt =
                ocfs2_block_dqtrailer(sb->s_blocksize, bh->b_data);

        trace_ocfs2_validate_quota_block((unsigned long long)bh->b_blocknr);

        BUG_ON(!buffer_uptodate(bh));

        /*
         * If the ecc fails, we return the error but otherwise
         * leave the filesystem running.  We know any error is
         * local to this block.
         */
        return ocfs2_validate_meta_ecc(sb, bh->b_data, &dqt->dq_check);
}

int ocfs2_read_quota_phys_block(struct inode *inode, u64 p_block,
                                struct buffer_head **bhp)
{
        int rc;

        *bhp = NULL;
        rc = ocfs2_read_blocks(INODE_CACHE(inode), p_block, 1, bhp, 0,
                               ocfs2_validate_quota_block);
        if (rc)
                mlog_errno(rc);
        return rc;
}

/* Read data from global quotafile - avoid pagecache and such because we cannot
 * afford acquiring the locks... We use quota cluster lock to serialize
 * operations. Caller is responsible for acquiring it. */
ssize_t ocfs2_quota_read(struct super_block *sb, int type, char *data,
                         size_t len, loff_t off)
{
        struct ocfs2_mem_dqinfo *oinfo = sb_dqinfo(sb, type)->dqi_priv;
        struct inode *gqinode = oinfo->dqi_gqinode;
        loff_t i_size = i_size_read(gqinode);
        int offset = off & (sb->s_blocksize - 1);
        sector_t blk = off >> sb->s_blocksize_bits;
        int err = 0;
        struct buffer_head *bh;
        size_t toread, tocopy;
        u64 pblock = 0, pcount = 0;

        if (off > i_size)
                return 0;
        if (off + len > i_size)
                len = i_size - off;
        toread = len;
        while (toread > 0) {
                tocopy = min_t(size_t, (sb->s_blocksize - offset), toread);
                if (!pcount) {
                        err = ocfs2_extent_map_get_blocks(gqinode, blk, &pblock,
                                                          &pcount, NULL);
                        if (err) {
                                mlog_errno(err);
                                return err;
                        }
                } else {
                        pcount--;
                        pblock++;
                }
                bh = NULL;
                err = ocfs2_read_quota_phys_block(gqinode, pblock, &bh);
                if (err) {
                        mlog_errno(err);
                        return err;
                }
                memcpy(data, bh->b_data + offset, tocopy);
                brelse(bh);
                offset = 0;
                toread -= tocopy;
                data += tocopy;
                blk++;
        }
        return len;
}

/* Write to quotafile (we know the transaction is already started and has
 * enough credits) */
ssize_t ocfs2_quota_write(struct super_block *sb, int type,
                          const char *data, size_t len, loff_t off)
{
        struct mem_dqinfo *info = sb_dqinfo(sb, type);
        struct ocfs2_mem_dqinfo *oinfo = info->dqi_priv;
        struct inode *gqinode = oinfo->dqi_gqinode;
        int offset = off & (sb->s_blocksize - 1);
        sector_t blk = off >> sb->s_blocksize_bits;
        int err = 0, new = 0, ja_type;
        struct buffer_head *bh = NULL;
        handle_t *handle = journal_current_handle();
        u64 pblock, pcount;

        if (!handle) {
                mlog(ML_ERROR, "Quota write (off=%llu, len=%llu) cancelled "
                     "because transaction was not started.\n",
                     (unsigned long long)off, (unsigned long long)len);
                return -EIO;
        }
        if (len > sb->s_blocksize - OCFS2_QBLK_RESERVED_SPACE - offset) {
                WARN_ON(1);
                len = sb->s_blocksize - OCFS2_QBLK_RESERVED_SPACE - offset;
        }

        if (i_size_read(gqinode) < off + len) {
                loff_t rounded_end =
                                ocfs2_align_bytes_to_blocks(sb, off + len);

                /* Space is already allocated in ocfs2_acquire_dquot() */
                err = ocfs2_simple_size_update(gqinode,
                                               oinfo->dqi_gqi_bh,
                                               rounded_end);
                if (err < 0)
                        goto out;
                new = 1;
        }
        err = ocfs2_extent_map_get_blocks(gqinode, blk, &pblock, &pcount, NULL);
        if (err) {
                mlog_errno(err);
                goto out;
        }
        /* Not rewriting whole block? */
        if ((offset || len < sb->s_blocksize - OCFS2_QBLK_RESERVED_SPACE) &&
            !new) {
                err = ocfs2_read_quota_phys_block(gqinode, pblock, &bh);
                ja_type = OCFS2_JOURNAL_ACCESS_WRITE;
        } else {
                bh = sb_getblk(sb, pblock);
                if (!bh)
                        err = -ENOMEM;
                ja_type = OCFS2_JOURNAL_ACCESS_CREATE;
        }
        if (err) {
                mlog_errno(err);
                goto out;
        }
        lock_buffer(bh);
        if (new)
                memset(bh->b_data, 0, sb->s_blocksize);
        memcpy(bh->b_data + offset, data, len);
        flush_dcache_page(bh->b_page);
        set_buffer_uptodate(bh);
        unlock_buffer(bh);
        ocfs2_set_buffer_uptodate(INODE_CACHE(gqinode), bh);
        err = ocfs2_journal_access_dq(handle, INODE_CACHE(gqinode), bh,
                                      ja_type);
        if (err < 0) {
                brelse(bh);
                goto out;
        }
        ocfs2_journal_dirty(handle, bh);
        brelse(bh);
out:
        if (err) {
                mlog_errno(err);
                return err;
        }
        gqinode->i_version++;
        ocfs2_mark_inode_dirty(handle, gqinode, oinfo->dqi_gqi_bh);
        return len;
}

int ocfs2_lock_global_qf(struct ocfs2_mem_dqinfo *oinfo, int ex)
{
        int status;
        struct buffer_head *bh = NULL;

        status = ocfs2_inode_lock(oinfo->dqi_gqinode, &bh, ex);
        if (status < 0)
                return status;
        spin_lock(&dq_data_lock);
        if (!oinfo->dqi_gqi_count++)
                oinfo->dqi_gqi_bh = bh;
        else
                WARN_ON(bh != oinfo->dqi_gqi_bh);
        spin_unlock(&dq_data_lock);
        if (ex) {
                inode_lock(oinfo->dqi_gqinode);
                down_write(&OCFS2_I(oinfo->dqi_gqinode)->ip_alloc_sem);
        } else {
                down_read(&OCFS2_I(oinfo->dqi_gqinode)->ip_alloc_sem);
        }
        return 0;
}

void ocfs2_unlock_global_qf(struct ocfs2_mem_dqinfo *oinfo, int ex)
{
        if (ex) {
                up_write(&OCFS2_I(oinfo->dqi_gqinode)->ip_alloc_sem);
                inode_unlock(oinfo->dqi_gqinode);
        } else {
                up_read(&OCFS2_I(oinfo->dqi_gqinode)->ip_alloc_sem);
        }
        ocfs2_inode_unlock(oinfo->dqi_gqinode, ex);
        brelse(oinfo->dqi_gqi_bh);
        spin_lock(&dq_data_lock);
        if (!--oinfo->dqi_gqi_count)
                oinfo->dqi_gqi_bh = NULL;
        spin_unlock(&dq_data_lock);
}

/* Read information header from global quota file */
int ocfs2_global_read_info(struct super_block *sb, int type)
{
        struct inode *gqinode = NULL;
        unsigned int ino[OCFS2_MAXQUOTAS] = { USER_QUOTA_SYSTEM_INODE,
                                              GROUP_QUOTA_SYSTEM_INODE };
        struct ocfs2_global_disk_dqinfo dinfo;
        struct mem_dqinfo *info = sb_dqinfo(sb, type);
        struct ocfs2_mem_dqinfo *oinfo = info->dqi_priv;
        u64 pcount;
        int status;

        /* Read global header */
        gqinode = ocfs2_get_system_file_inode(OCFS2_SB(sb), ino[type],
                        OCFS2_INVALID_SLOT);
        if (!gqinode) {
                mlog(ML_ERROR, "failed to get global quota inode (type=%d)\n",
                        type);
                status = -EINVAL;
                goto out_err;
        }
        oinfo->dqi_gi.dqi_sb = sb;
        oinfo->dqi_gi.dqi_type = type;
        ocfs2_qinfo_lock_res_init(&oinfo->dqi_gqlock, oinfo);
        oinfo->dqi_gi.dqi_entry_size = sizeof(struct ocfs2_global_disk_dqblk);
        oinfo->dqi_gi.dqi_ops = &ocfs2_global_ops;
        oinfo->dqi_gqi_bh = NULL;
        oinfo->dqi_gqi_count = 0;
        oinfo->dqi_gqinode = gqinode;
        status = ocfs2_lock_global_qf(oinfo, 0);
        if (status < 0) {
                mlog_errno(status);
                goto out_err;
        }

        status = ocfs2_extent_map_get_blocks(gqinode, 0, &oinfo->dqi_giblk,
                                             &pcount, NULL);
        if (status < 0)
                goto out_unlock;

        status = ocfs2_qinfo_lock(oinfo, 0);
        if (status < 0)
                goto out_unlock;
        status = sb->s_op->quota_read(sb, type, (char *)&dinfo,
                                      sizeof(struct ocfs2_global_disk_dqinfo),
                                      OCFS2_GLOBAL_INFO_OFF);
        ocfs2_qinfo_unlock(oinfo, 0);
        ocfs2_unlock_global_qf(oinfo, 0);
        if (status != sizeof(struct ocfs2_global_disk_dqinfo)) {
                mlog(ML_ERROR, "Cannot read global quota info (%d).\n",
                     status);
                if (status >= 0)
                        status = -EIO;
                mlog_errno(status);
                goto out_err;
        }
        info->dqi_bgrace = le32_to_cpu(dinfo.dqi_bgrace);
        info->dqi_igrace = le32_to_cpu(dinfo.dqi_igrace);
        oinfo->dqi_syncms = le32_to_cpu(dinfo.dqi_syncms);
        oinfo->dqi_gi.dqi_blocks = le32_to_cpu(dinfo.dqi_blocks);
        oinfo->dqi_gi.dqi_free_blk = le32_to_cpu(dinfo.dqi_free_blk);
        oinfo->dqi_gi.dqi_free_entry = le32_to_cpu(dinfo.dqi_free_entry);
        oinfo->dqi_gi.dqi_blocksize_bits = sb->s_blocksize_bits;
        oinfo->dqi_gi.dqi_usable_bs = sb->s_blocksize -
                                                OCFS2_QBLK_RESERVED_SPACE;
        oinfo->dqi_gi.dqi_qtree_depth = qtree_depth(&oinfo->dqi_gi);
        INIT_DELAYED_WORK(&oinfo->dqi_sync_work, qsync_work_fn);
        schedule_delayed_work(&oinfo->dqi_sync_work,
                              msecs_to_jiffies(oinfo->dqi_syncms));

out_err:
        return status;
out_unlock:
        ocfs2_unlock_global_qf(oinfo, 0);
        mlog_errno(status);
        goto out_err;
}

/* Write information to global quota file. Expects exlusive lock on quota
 * file inode and quota info */
static int __ocfs2_global_write_info(struct super_block *sb, int type)
{
        struct mem_dqinfo *info = sb_dqinfo(sb, type);
        struct ocfs2_mem_dqinfo *oinfo = info->dqi_priv;
        struct ocfs2_global_disk_dqinfo dinfo;
        ssize_t size;

        spin_lock(&dq_data_lock);
        info->dqi_flags &= ~DQF_INFO_DIRTY;
        dinfo.dqi_bgrace = cpu_to_le32(info->dqi_bgrace);
        dinfo.dqi_igrace = cpu_to_le32(info->dqi_igrace);
        spin_unlock(&dq_data_lock);
        dinfo.dqi_syncms = cpu_to_le32(oinfo->dqi_syncms);
        dinfo.dqi_blocks = cpu_to_le32(oinfo->dqi_gi.dqi_blocks);
        dinfo.dqi_free_blk = cpu_to_le32(oinfo->dqi_gi.dqi_free_blk);
        dinfo.dqi_free_entry = cpu_to_le32(oinfo->dqi_gi.dqi_free_entry);
        size = sb->s_op->quota_write(sb, type, (char *)&dinfo,
                                     sizeof(struct ocfs2_global_disk_dqinfo),
                                     OCFS2_GLOBAL_INFO_OFF);
        if (size != sizeof(struct ocfs2_global_disk_dqinfo)) {
                mlog(ML_ERROR, "Cannot write global quota info structure\n");
                if (size >= 0)
                        size = -EIO;
                return size;
        }
        return 0;
}

int ocfs2_global_write_info(struct super_block *sb, int type)
{
        int err;
        struct quota_info *dqopt = sb_dqopt(sb);
        struct ocfs2_mem_dqinfo *info = dqopt->info[type].dqi_priv;

        down_write(&dqopt->dqio_sem);
        err = ocfs2_qinfo_lock(info, 1);
        if (err < 0)
                goto out_sem;
        err = __ocfs2_global_write_info(sb, type);
        ocfs2_qinfo_unlock(info, 1);
out_sem:
        up_write(&dqopt->dqio_sem);
        return err;
}

static int ocfs2_global_qinit_alloc(struct super_block *sb, int type)
{
        struct ocfs2_mem_dqinfo *oinfo = sb_dqinfo(sb, type)->dqi_priv;

        /*
         * We may need to allocate tree blocks and a leaf block but not the
         * root block
         */
        return oinfo->dqi_gi.dqi_qtree_depth;
}

static int ocfs2_calc_global_qinit_credits(struct super_block *sb, int type)
{
        /* We modify all the allocated blocks, tree root, info block and
         * the inode */
        return (ocfs2_global_qinit_alloc(sb, type) + 2) *
                        OCFS2_QUOTA_BLOCK_UPDATE_CREDITS + 1;
}

/* Sync local information about quota modifications with global quota file.
 * Caller must have started the transaction and obtained exclusive lock for
 * global quota file inode */
int __ocfs2_sync_dquot(struct dquot *dquot, int freeing)
{
        int err, err2;
        struct super_block *sb = dquot->dq_sb;
        int type = dquot->dq_id.type;
        struct ocfs2_mem_dqinfo *info = sb_dqinfo(sb, type)->dqi_priv;
        struct ocfs2_global_disk_dqblk dqblk;
        s64 spacechange, inodechange;
        time64_t olditime, oldbtime;

        err = sb->s_op->quota_read(sb, type, (char *)&dqblk,
                                   sizeof(struct ocfs2_global_disk_dqblk),
                                   dquot->dq_off);
        if (err != sizeof(struct ocfs2_global_disk_dqblk)) {
                if (err >= 0) {
                        mlog(ML_ERROR, "Short read from global quota file "
                                       "(%u read)\n", err);
                        err = -EIO;
                }
                goto out;
        }

        /* Update space and inode usage. Get also other information from
         * global quota file so that we don't overwrite any changes there.
         * We are */
        spin_lock(&dquot->dq_dqb_lock);
        spacechange = dquot->dq_dqb.dqb_curspace -
                                        OCFS2_DQUOT(dquot)->dq_origspace;
        inodechange = dquot->dq_dqb.dqb_curinodes -
                                        OCFS2_DQUOT(dquot)->dq_originodes;
        olditime = dquot->dq_dqb.dqb_itime;
        oldbtime = dquot->dq_dqb.dqb_btime;
        ocfs2_global_disk2memdqb(dquot, &dqblk);
        trace_ocfs2_sync_dquot(from_kqid(&init_user_ns, dquot->dq_id),
                               dquot->dq_dqb.dqb_curspace,
                               (long long)spacechange,
                               dquot->dq_dqb.dqb_curinodes,
                               (long long)inodechange);
        if (!test_bit(DQ_LASTSET_B + QIF_SPACE_B, &dquot->dq_flags))
                dquot->dq_dqb.dqb_curspace += spacechange;
        if (!test_bit(DQ_LASTSET_B + QIF_INODES_B, &dquot->dq_flags))
                dquot->dq_dqb.dqb_curinodes += inodechange;
        /* Set properly space grace time... */
        if (dquot->dq_dqb.dqb_bsoftlimit &&
            dquot->dq_dqb.dqb_curspace > dquot->dq_dqb.dqb_bsoftlimit) {
                if (!test_bit(DQ_LASTSET_B + QIF_BTIME_B, &dquot->dq_flags) &&
                    oldbtime > 0) {
                        if (dquot->dq_dqb.dqb_btime > 0)
                                dquot->dq_dqb.dqb_btime =
                                        min(dquot->dq_dqb.dqb_btime, oldbtime);
                        else
                                dquot->dq_dqb.dqb_btime = oldbtime;
                }
        } else {
                dquot->dq_dqb.dqb_btime = 0;
                clear_bit(DQ_BLKS_B, &dquot->dq_flags);
        }
        /* Set properly inode grace time... */
        if (dquot->dq_dqb.dqb_isoftlimit &&
            dquot->dq_dqb.dqb_curinodes > dquot->dq_dqb.dqb_isoftlimit) {
                if (!test_bit(DQ_LASTSET_B + QIF_ITIME_B, &dquot->dq_flags) &&
                    olditime > 0) {
                        if (dquot->dq_dqb.dqb_itime > 0)
                                dquot->dq_dqb.dqb_itime =
                                        min(dquot->dq_dqb.dqb_itime, olditime);
                        else
                                dquot->dq_dqb.dqb_itime = olditime;
                }
        } else {
                dquot->dq_dqb.dqb_itime = 0;
                clear_bit(DQ_INODES_B, &dquot->dq_flags);
        }
        /* All information is properly updated, clear the flags */
        __clear_bit(DQ_LASTSET_B + QIF_SPACE_B, &dquot->dq_flags);
        __clear_bit(DQ_LASTSET_B + QIF_INODES_B, &dquot->dq_flags);
        __clear_bit(DQ_LASTSET_B + QIF_BLIMITS_B, &dquot->dq_flags);
        __clear_bit(DQ_LASTSET_B + QIF_ILIMITS_B, &dquot->dq_flags);
        __clear_bit(DQ_LASTSET_B + QIF_BTIME_B, &dquot->dq_flags);
        __clear_bit(DQ_LASTSET_B + QIF_ITIME_B, &dquot->dq_flags);
        OCFS2_DQUOT(dquot)->dq_origspace = dquot->dq_dqb.dqb_curspace;
        OCFS2_DQUOT(dquot)->dq_originodes = dquot->dq_dqb.dqb_curinodes;
        spin_unlock(&dquot->dq_dqb_lock);
        err = ocfs2_qinfo_lock(info, freeing);
        if (err < 0) {
                mlog(ML_ERROR, "Failed to lock quota info, losing quota write"
                               " (type=%d, id=%u)\n", dquot->dq_id.type,
                               (unsigned)from_kqid(&init_user_ns, dquot->dq_id));
                goto out;
        }
        if (freeing)
                OCFS2_DQUOT(dquot)->dq_use_count--;
        err = qtree_write_dquot(&info->dqi_gi, dquot);
        if (err < 0)
                goto out_qlock;
        if (freeing && !OCFS2_DQUOT(dquot)->dq_use_count) {
                err = qtree_release_dquot(&info->dqi_gi, dquot);
                if (info_dirty(sb_dqinfo(sb, type))) {
                        err2 = __ocfs2_global_write_info(sb, type);
                        if (!err)
                                err = err2;
                }
        }
out_qlock:
        ocfs2_qinfo_unlock(info, freeing);
out:
        if (err < 0)
                mlog_errno(err);
        return err;
}

/*
 *  Functions for periodic syncing of dquots with global file
 */
static int ocfs2_sync_dquot_helper(struct dquot *dquot, unsigned long type)
{
        handle_t *handle;
        struct super_block *sb = dquot->dq_sb;
        struct ocfs2_mem_dqinfo *oinfo = sb_dqinfo(sb, type)->dqi_priv;
        struct ocfs2_super *osb = OCFS2_SB(sb);
        int status = 0;

        trace_ocfs2_sync_dquot_helper(from_kqid(&init_user_ns, dquot->dq_id),
                                      dquot->dq_id.type,
                                      type, sb->s_id);
        if (type != dquot->dq_id.type)
                goto out;
        status = ocfs2_lock_global_qf(oinfo, 1);
        if (status < 0)
                goto out;

        handle = ocfs2_start_trans(osb, OCFS2_QSYNC_CREDITS);
        if (IS_ERR(handle)) {
                status = PTR_ERR(handle);
                mlog_errno(status);
                goto out_ilock;
        }
        down_write(&sb_dqopt(sb)->dqio_sem);
        status = ocfs2_sync_dquot(dquot);
        if (status < 0)
                mlog_errno(status);
        /* We have to write local structure as well... */
        status = ocfs2_local_write_dquot(dquot);
        if (status < 0)
                mlog_errno(status);
        up_write(&sb_dqopt(sb)->dqio_sem);
        ocfs2_commit_trans(osb, handle);
out_ilock:
        ocfs2_unlock_global_qf(oinfo, 1);
out:
        return status;
}

static void qsync_work_fn(struct work_struct *work)
{
        struct ocfs2_mem_dqinfo *oinfo = container_of(work,
                                                      struct ocfs2_mem_dqinfo,
                                                      dqi_sync_work.work);
        struct super_block *sb = oinfo->dqi_gqinode->i_sb;

        /*
         * We have to be careful here not to deadlock on s_umount as umount
         * disabling quotas may be in progress and it waits for this work to
         * complete. If trylock fails, we'll do the sync next time...
         */
        if (down_read_trylock(&sb->s_umount)) {
                dquot_scan_active(sb, ocfs2_sync_dquot_helper, oinfo->dqi_type);
                up_read(&sb->s_umount);
        }
        schedule_delayed_work(&oinfo->dqi_sync_work,
                              msecs_to_jiffies(oinfo->dqi_syncms));
}

/*
 *  Wrappers for generic quota functions
 */

static int ocfs2_write_dquot(struct dquot *dquot)
{
        handle_t *handle;
        struct ocfs2_super *osb = OCFS2_SB(dquot->dq_sb);
        int status = 0;

        trace_ocfs2_write_dquot(from_kqid(&init_user_ns, dquot->dq_id),
                                dquot->dq_id.type);

        handle = ocfs2_start_trans(osb, OCFS2_QWRITE_CREDITS);
        if (IS_ERR(handle)) {
                status = PTR_ERR(handle);
                mlog_errno(status);
                goto out;
        }
        down_write(&sb_dqopt(dquot->dq_sb)->dqio_sem);
        status = ocfs2_local_write_dquot(dquot);
        up_write(&sb_dqopt(dquot->dq_sb)->dqio_sem);
        ocfs2_commit_trans(osb, handle);
out:
        return status;
}

static int ocfs2_calc_qdel_credits(struct super_block *sb, int type)
{
        struct ocfs2_mem_dqinfo *oinfo = sb_dqinfo(sb, type)->dqi_priv;
        /*
         * We modify tree, leaf block, global info, local chunk header,
         * global and local inode; OCFS2_QINFO_WRITE_CREDITS already
         * accounts for inode update
         */
        return (oinfo->dqi_gi.dqi_qtree_depth + 2) *
               OCFS2_QUOTA_BLOCK_UPDATE_CREDITS +
               OCFS2_QINFO_WRITE_CREDITS +
               OCFS2_INODE_UPDATE_CREDITS;
}

void ocfs2_drop_dquot_refs(struct work_struct *work)
{
        struct ocfs2_super *osb = container_of(work, struct ocfs2_super,
                                               dquot_drop_work);
        struct llist_node *list;
        struct ocfs2_dquot *odquot, *next_odquot;

        list = llist_del_all(&osb->dquot_drop_list);
        llist_for_each_entry_safe(odquot, next_odquot, list, list) {
                /* Drop the reference we acquired in ocfs2_dquot_release() */
                dqput(&odquot->dq_dquot);
        }
}

/*
 * Called when the last reference to dquot is dropped. If we are called from
 * downconvert thread, we cannot do all the handling here because grabbing
 * quota lock could deadlock (the node holding the quota lock could need some
 * other cluster lock to proceed but with blocked downconvert thread we cannot
 * release any lock).
 */
static int ocfs2_release_dquot(struct dquot *dquot)
{
        handle_t *handle;
        struct ocfs2_mem_dqinfo *oinfo =
                        sb_dqinfo(dquot->dq_sb, dquot->dq_id.type)->dqi_priv;
        struct ocfs2_super *osb = OCFS2_SB(dquot->dq_sb);
        int status = 0;

        trace_ocfs2_release_dquot(from_kqid(&init_user_ns, dquot->dq_id),
                                  dquot->dq_id.type);

        mutex_lock(&dquot->dq_lock);
        /* Check whether we are not racing with some other dqget() */
        if (dquot_is_busy(dquot))
                goto out;
        /* Running from downconvert thread? Postpone quota processing to wq */
        if (current == osb->dc_task) {
                /*
                 * Grab our own reference to dquot and queue it for delayed
                 * dropping.  Quota code rechecks after calling
                 * ->release_dquot() and won't free dquot structure.
                 */
                dqgrab(dquot);
                /* First entry on list -> queue work */
                if (llist_add(&OCFS2_DQUOT(dquot)->list, &osb->dquot_drop_list))
                        queue_work(osb->ocfs2_wq, &osb->dquot_drop_work);
                goto out;
        }
        status = ocfs2_lock_global_qf(oinfo, 1);
        if (status < 0)
                goto out;
        handle = ocfs2_start_trans(osb,
                ocfs2_calc_qdel_credits(dquot->dq_sb, dquot->dq_id.type));
        if (IS_ERR(handle)) {
                status = PTR_ERR(handle);
                mlog_errno(status);
                goto out_ilock;
        }

        status = ocfs2_global_release_dquot(dquot);
        if (status < 0) {
                mlog_errno(status);
                goto out_trans;
        }
        status = ocfs2_local_release_dquot(handle, dquot);
        /*
         * If we fail here, we cannot do much as global structure is
         * already released. So just complain...
         */
        if (status < 0)
                mlog_errno(status);
        /*
         * Clear dq_off so that we search for the structure in quota file next
         * time we acquire it. The structure might be deleted and reallocated
         * elsewhere by another node while our dquot structure is on freelist.
         */
        dquot->dq_off = 0;
        clear_bit(DQ_ACTIVE_B, &dquot->dq_flags);
out_trans:
        ocfs2_commit_trans(osb, handle);
out_ilock:
        ocfs2_unlock_global_qf(oinfo, 1);
out:
        mutex_unlock(&dquot->dq_lock);
        if (status)
                mlog_errno(status);
        return status;
}

/*
 * Read global dquot structure from disk or create it if it does
 * not exist. Also update use count of the global structure and
 * create structure in node-local quota file.
 */
static int ocfs2_acquire_dquot(struct dquot *dquot)
{
        int status = 0, err;
        int ex = 0;
        struct super_block *sb = dquot->dq_sb;
        struct ocfs2_super *osb = OCFS2_SB(sb);
        int type = dquot->dq_id.type;
        struct ocfs2_mem_dqinfo *info = sb_dqinfo(sb, type)->dqi_priv;
        struct inode *gqinode = info->dqi_gqinode;
        int need_alloc = ocfs2_global_qinit_alloc(sb, type);
        handle_t *handle;

        trace_ocfs2_acquire_dquot(from_kqid(&init_user_ns, dquot->dq_id),
                                  type);
        mutex_lock(&dquot->dq_lock);
        /*
         * We need an exclusive lock, because we're going to update use count
         * and instantiate possibly new dquot structure
         */
        status = ocfs2_lock_global_qf(info, 1);
        if (status < 0)
                goto out;
        status = ocfs2_qinfo_lock(info, 0);
        if (status < 0)
                goto out_dq;
        /*
         * We always want to read dquot structure from disk because we don't
         * know what happened with it while it was on freelist.
         */
        status = qtree_read_dquot(&info->dqi_gi, dquot);
        ocfs2_qinfo_unlock(info, 0);
        if (status < 0)
                goto out_dq;

        OCFS2_DQUOT(dquot)->dq_use_count++;
        OCFS2_DQUOT(dquot)->dq_origspace = dquot->dq_dqb.dqb_curspace;
        OCFS2_DQUOT(dquot)->dq_originodes = dquot->dq_dqb.dqb_curinodes;
        if (!dquot->dq_off) {   /* No real quota entry? */
                ex = 1;
                /*
                 * Add blocks to quota file before we start a transaction since
                 * locking allocators ranks above a transaction start
                 */
                WARN_ON(journal_current_handle());
                status = ocfs2_extend_no_holes(gqinode, NULL,
                        i_size_read(gqinode) + (need_alloc << sb->s_blocksize_bits),
                        i_size_read(gqinode));
                if (status < 0)
                        goto out_dq;
        }

        handle = ocfs2_start_trans(osb,
                                   ocfs2_calc_global_qinit_credits(sb, type));
        if (IS_ERR(handle)) {
                status = PTR_ERR(handle);
                goto out_dq;
        }
        status = ocfs2_qinfo_lock(info, ex);
        if (status < 0)
                goto out_trans;
        status = qtree_write_dquot(&info->dqi_gi, dquot);
        if (ex && info_dirty(sb_dqinfo(sb, type))) {
                err = __ocfs2_global_write_info(sb, type);
                if (!status)
                        status = err;
        }
        ocfs2_qinfo_unlock(info, ex);
out_trans:
        ocfs2_commit_trans(osb, handle);
out_dq:
        ocfs2_unlock_global_qf(info, 1);
        if (status < 0)
                goto out;

        status = ocfs2_create_local_dquot(dquot);
        if (status < 0)
                goto out;
        set_bit(DQ_ACTIVE_B, &dquot->dq_flags);
out:
        mutex_unlock(&dquot->dq_lock);
        if (status)
                mlog_errno(status);
        return status;
}

static int ocfs2_get_next_id(struct super_block *sb, struct kqid *qid)
{
        int type = qid->type;
        struct ocfs2_mem_dqinfo *info = sb_dqinfo(sb, type)->dqi_priv;
        int status = 0;

        trace_ocfs2_get_next_id(from_kqid(&init_user_ns, *qid), type);
        if (!sb_has_quota_loaded(sb, type)) {
                status = -ESRCH;
                goto out;
        }
        status = ocfs2_lock_global_qf(info, 0);
        if (status < 0)
                goto out;
        status = ocfs2_qinfo_lock(info, 0);
        if (status < 0)
                goto out_global;
        status = qtree_get_next_id(&info->dqi_gi, qid);
        ocfs2_qinfo_unlock(info, 0);
out_global:
        ocfs2_unlock_global_qf(info, 0);
out:
        /*
         * Avoid logging ENOENT since it just means there isn't next ID and
         * ESRCH which means quota isn't enabled for the filesystem.
         */
        if (status && status != -ENOENT && status != -ESRCH)
                mlog_errno(status);
        return status;
}

static int ocfs2_mark_dquot_dirty(struct dquot *dquot)
{
        unsigned long mask = (1 << (DQ_LASTSET_B + QIF_ILIMITS_B)) |
                             (1 << (DQ_LASTSET_B + QIF_BLIMITS_B)) |
                             (1 << (DQ_LASTSET_B + QIF_INODES_B)) |
                             (1 << (DQ_LASTSET_B + QIF_SPACE_B)) |
                             (1 << (DQ_LASTSET_B + QIF_BTIME_B)) |
                             (1 << (DQ_LASTSET_B + QIF_ITIME_B));
        int sync = 0;
        int status;
        struct super_block *sb = dquot->dq_sb;
        int type = dquot->dq_id.type;
        struct ocfs2_mem_dqinfo *oinfo = sb_dqinfo(sb, type)->dqi_priv;
        handle_t *handle;
        struct ocfs2_super *osb = OCFS2_SB(sb);

        trace_ocfs2_mark_dquot_dirty(from_kqid(&init_user_ns, dquot->dq_id),
                                     type);

        /* In case user set some limits, sync dquot immediately to global
         * quota file so that information propagates quicker */
        spin_lock(&dquot->dq_dqb_lock);
        if (dquot->dq_flags & mask)
                sync = 1;
        spin_unlock(&dquot->dq_dqb_lock);
        /* This is a slight hack but we can't afford getting global quota
         * lock if we already have a transaction started. */
        if (!sync || journal_current_handle()) {
                status = ocfs2_write_dquot(dquot);
                goto out;
        }
        status = ocfs2_lock_global_qf(oinfo, 1);
        if (status < 0)
                goto out;
        handle = ocfs2_start_trans(osb, OCFS2_QSYNC_CREDITS);
        if (IS_ERR(handle)) {
                status = PTR_ERR(handle);
                mlog_errno(status);
                goto out_ilock;
        }
        down_write(&sb_dqopt(sb)->dqio_sem);
        status = ocfs2_sync_dquot(dquot);
        if (status < 0) {
                mlog_errno(status);
                goto out_dlock;
        }
        /* Now write updated local dquot structure */
        status = ocfs2_local_write_dquot(dquot);
out_dlock:
        up_write(&sb_dqopt(sb)->dqio_sem);
        ocfs2_commit_trans(osb, handle);
out_ilock:
        ocfs2_unlock_global_qf(oinfo, 1);
out:
        if (status)
                mlog_errno(status);
        return status;
}

/* This should happen only after set_dqinfo(). */
static int ocfs2_write_info(struct super_block *sb, int type)
{
        handle_t *handle;
        int status = 0;
        struct ocfs2_mem_dqinfo *oinfo = sb_dqinfo(sb, type)->dqi_priv;

        status = ocfs2_lock_global_qf(oinfo, 1);
        if (status < 0)
                goto out;
        handle = ocfs2_start_trans(OCFS2_SB(sb), OCFS2_QINFO_WRITE_CREDITS);
        if (IS_ERR(handle)) {
                status = PTR_ERR(handle);
                mlog_errno(status);
                goto out_ilock;
        }
        status = dquot_commit_info(sb, type);
        ocfs2_commit_trans(OCFS2_SB(sb), handle);
out_ilock:
        ocfs2_unlock_global_qf(oinfo, 1);
out:
        if (status)
                mlog_errno(status);
        return status;
}

static struct dquot *ocfs2_alloc_dquot(struct super_block *sb, int type)
{
        struct ocfs2_dquot *dquot =
                                kmem_cache_zalloc(ocfs2_dquot_cachep, GFP_NOFS);

        if (!dquot)
                return NULL;
        return &dquot->dq_dquot;
}

static void ocfs2_destroy_dquot(struct dquot *dquot)
{
        kmem_cache_free(ocfs2_dquot_cachep, dquot);
}

const struct dquot_operations ocfs2_quota_operations = {
        /* We never make dquot dirty so .write_dquot is never called */
        .acquire_dquot  = ocfs2_acquire_dquot,
        .release_dquot  = ocfs2_release_dquot,
        .mark_dirty     = ocfs2_mark_dquot_dirty,
        .write_info     = ocfs2_write_info,
        .alloc_dquot    = ocfs2_alloc_dquot,
        .destroy_dquot  = ocfs2_destroy_dquot,
        .get_next_id    = ocfs2_get_next_id,
};