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quota.c

/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
 * Copyright (C) 2004-2006 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 to a quota check
 * program to be run on node crashes or anything like that.
 *
 * There are couple of knobs that let the administrator manage the quota
 * fuzziness.  "quota_quantum" sets the maximum time a quota change can be
 * sitting on one node before being synced to the quota file.  (The default is
 * 60 seconds.)  Another knob, "quota_scale" controls how quickly the frequency
 * of quota file syncs increases as the user moves closer to their limit.  The
 * more frequent the syncs, the more accurate the quota enforcement, but that
 * means that there is more contention between the nodes for the quota file.
 * The default value is one.  This sets the maximum theoretical quota overrun
 * (with infinite node with infinite bandwidth) to twice the user's limit.  (In
 * practice, the maximum overrun you see should be much less.)  A "quota_scale"
 * number greater than one makes quota syncs more frequent and reduces the
 * maximum overrun.  Numbers less than one (but greater than zero) make quota
 * syncs less frequent.
 *
 * GFS quotas also use per-ID Lock Value Blocks (LVBs) to cache the contents of
 * the quota file, so it is not being constantly read.
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/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/lm_interface.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 "ops_file.h"
#include "ops_address.h"
#include "util.h"

#define QUOTA_USER 1
#define QUOTA_GROUP 0

struct gfs2_quota_host {
      u64 qu_limit;
      u64 qu_warn;
      s64 qu_value;
      u32 qu_ll_next;
};

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

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

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

      return offset;
}

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

      qd = kzalloc(sizeof(struct gfs2_quota_data), GFP_KERNEL);
      if (!qd)
            return -ENOMEM;

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

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

      error = gfs2_lvb_hold(qd->qd_gl);
      gfs2_glock_put(qd->qd_gl);
      if (error)
            goto fail;

      *qdp = qd;

      return 0;

fail:
      kfree(qd);
      return error;
}

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

      *qdp = NULL;

      for (;;) {
            found = 0;
            spin_lock(&sdp->sd_quota_spin);
            list_for_each_entry(qd, &sdp->sd_quota_list, qd_list) {
                  if (qd->qd_id == id &&
                      !test_bit(QDF_USER, &qd->qd_flags) == !user) {
                        qd->qd_count++;
                        found = 1;
                        break;
                  }
            }

            if (!found)
                  qd = NULL;

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

            spin_unlock(&sdp->sd_quota_spin);

            if (qd || !create) {
                  if (new_qd) {
                        gfs2_lvb_unhold(new_qd->qd_gl);
                        kfree(new_qd);
                  }
                  *qdp = qd;
                  return 0;
            }

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

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

      spin_lock(&sdp->sd_quota_spin);
      gfs2_assert(sdp, qd->qd_count);
      qd->qd_count++;
      spin_unlock(&sdp->sd_quota_spin);
}

static void qd_put(struct gfs2_quota_data *qd)
{
      struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;
      spin_lock(&sdp->sd_quota_spin);
      gfs2_assert(sdp, qd->qd_count);
      if (!--qd->qd_count)
            qd->qd_last_touched = jiffies;
      spin_unlock(&sdp->sd_quota_spin);
}

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

      spin_lock(&sdp->sd_quota_spin);

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

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

      goto fail;

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

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

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

      spin_unlock(&sdp->sd_quota_spin);

      return 0;

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

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

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

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

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

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

      mutex_lock(&sdp->sd_quota_mutex);

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

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

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

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

      mutex_unlock(&sdp->sd_quota_mutex);

      return 0;

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

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

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

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

      *qdp = NULL;

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

      spin_lock(&sdp->sd_quota_spin);

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

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

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

            break;
      }

      if (!found)
            qd = NULL;

      spin_unlock(&sdp->sd_quota_spin);

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

      *qdp = qd;

      return 0;
}

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

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

      spin_lock(&sdp->sd_quota_spin);

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

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

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

      spin_unlock(&sdp->sd_quota_spin);

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

      return 1;
}

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

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

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

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

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

      return 0;

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

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

int gfs2_quota_hold(struct gfs2_inode *ip, u32 uid, u32 gid)
{
      struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
      struct gfs2_alloc *al = &ip->i_alloc;
      struct gfs2_quota_data **qd = al->al_qd;
      int error;

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

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

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

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

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

      if (gid != NO_QUOTA_CHANGE && gid != ip->i_inode.i_gid) {
            error = qdsb_get(sdp, QUOTA_GROUP, gid, CREATE, qd);
            if (error)
                  goto out;
            al->al_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);
      struct gfs2_alloc *al = &ip->i_alloc;
      unsigned int x;

      gfs2_assert_warn(sdp, !test_bit(GIF_QD_LOCKED, &ip->i_flags));

      for (x = 0; x < al->al_qd_num; x++) {
            qdsb_put(al->al_qd[x]);
            al->al_qd[x] = NULL;
      }
      al->al_qd_num = 0;
}

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

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

      return 0;
}

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

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

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

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

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

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

      mutex_unlock(&sdp->sd_quota_mutex);
}

static void gfs2_quota_in(struct gfs2_quota_host *qu, const void *buf)
{
      const struct gfs2_quota *str = buf;

      qu->qu_limit = be64_to_cpu(str->qu_limit);
      qu->qu_warn = be64_to_cpu(str->qu_warn);
      qu->qu_value = be64_to_cpu(str->qu_value);
      qu->qu_ll_next = be32_to_cpu(str->qu_ll_next);
}

static void gfs2_quota_out(const struct gfs2_quota_host *qu, void *buf)
{
      struct gfs2_quota *str = buf;

      str->qu_limit = cpu_to_be64(qu->qu_limit);
      str->qu_warn = cpu_to_be64(qu->qu_warn);
      str->qu_value = cpu_to_be64(qu->qu_value);
      str->qu_ll_next = cpu_to_be32(qu->qu_ll_next);
      memset(&str->qu_reserved, 0, sizeof(str->qu_reserved));
}

/**
 * gfs2_adjust_quota
 *
 * This function was mostly borrowed from gfs2_block_truncate_page which was
 * in turn mostly borrowed from ext3
 */
static int gfs2_adjust_quota(struct gfs2_inode *ip, loff_t loc,
                       s64 change, struct gfs2_quota_data *qd)
{
      struct inode *inode = &ip->i_inode;
      struct address_space *mapping = inode->i_mapping;
      unsigned long index = loc >> PAGE_CACHE_SHIFT;
      unsigned offset = loc & (PAGE_CACHE_SIZE - 1);
      unsigned blocksize, iblock, pos;
      struct buffer_head *bh;
      struct page *page;
      void *kaddr;
      char *ptr;
      struct gfs2_quota_host qp;
      s64 value;
      int err = -EIO;

      if (gfs2_is_stuffed(ip)) {
            struct gfs2_alloc *al = NULL;
            al = gfs2_alloc_get(ip);
            /* just request 1 blk */
            al->al_requested = 1;
            gfs2_inplace_reserve(ip);
            gfs2_unstuff_dinode(ip, NULL);
            gfs2_inplace_release(ip);
            gfs2_alloc_put(ip);
      }
      page = grab_cache_page(mapping, index);
      if (!page)
            return -ENOMEM;

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

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

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

      if (!buffer_mapped(bh)) {
            gfs2_get_block(inode, iblock, bh, 1);
            if (!buffer_mapped(bh))
                  goto unlock;
      }

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

      if (!buffer_uptodate(bh)) {
            ll_rw_block(READ_META, 1, &bh);
            wait_on_buffer(bh);
            if (!buffer_uptodate(bh))
                  goto unlock;
      }

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

      kaddr = kmap_atomic(page, KM_USER0);
      ptr = kaddr + offset;
      gfs2_quota_in(&qp, ptr);
      qp.qu_value += change;
      value = qp.qu_value;
      gfs2_quota_out(&qp, ptr);
      flush_dcache_page(page);
      kunmap_atomic(kaddr, KM_USER0);
      err = 0;
      qd->qd_qb.qb_magic = cpu_to_be32(GFS2_MAGIC);
      qd->qd_qb.qb_value = cpu_to_be64(value);
      ((struct gfs2_quota_lvb*)(qd->qd_gl->gl_lvb))->qb_magic = cpu_to_be32(GFS2_MAGIC);
      ((struct gfs2_quota_lvb*)(qd->qd_gl->gl_lvb))->qb_value = cpu_to_be64(value);
unlock:
      unlock_page(page);
      page_cache_release(page);
      return err;
}

static int do_sync(unsigned int num_qd, struct gfs2_quota_data **qda)
{
      struct gfs2_sbd *sdp = (*qda)->qd_gl->gl_sbd;
      struct gfs2_inode *ip = GFS2_I(sdp->sd_quota_inode);
      unsigned int data_blocks, ind_blocks;
      struct gfs2_holder *ghs, i_gh;
      unsigned int qx, x;
      struct gfs2_quota_data *qd;
      loff_t offset;
      unsigned int nalloc = 0;
      struct gfs2_alloc *al = NULL;
      int error;

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

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

      sort(qda, num_qd, sizeof(struct gfs2_quota_data *), sort_qd, NULL);
      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++) {
            int alloc_required;

            offset = qd2offset(qda[x]);
            error = gfs2_write_alloc_required(ip, offset,
                                      sizeof(struct gfs2_quota),
                                      &alloc_required);
            if (error)
                  goto out_gunlock;
            if (alloc_required)
                  nalloc++;
      }

      if (nalloc) {
            al = gfs2_alloc_get(ip);

            al->al_requested = nalloc * (data_blocks + ind_blocks);

            error = gfs2_inplace_reserve(ip);
            if (error)
                  goto out_alloc;

            error = gfs2_trans_begin(sdp,
                               al->al_rgd->rd_length +
                               num_qd * data_blocks +
                               nalloc * ind_blocks +
                               RES_DINODE + num_qd +
                               RES_STATFS, 0);
            if (error)
                  goto out_ipres;
      } else {
            error = gfs2_trans_begin(sdp,
                               num_qd * data_blocks +
                               RES_DINODE + num_qd, 0);
            if (error)
                  goto out_gunlock;
      }

      for (x = 0; x < num_qd; x++) {
            qd = qda[x];
            offset = qd2offset(qd);
            error = gfs2_adjust_quota(ip, offset, qd->qd_change_sync,
                                (struct gfs2_quota_data *)
                                qd);
            if (error)
                  goto out_end_trans;

            do_qc(qd, -qd->qd_change_sync);
      }

      error = 0;

out_end_trans:
      gfs2_trans_end(sdp);
out_ipres:
      if (nalloc)
            gfs2_inplace_release(ip);
out_alloc:
      if (nalloc)
            gfs2_alloc_put(ip);
out_gunlock:
      gfs2_glock_dq_uninit(&i_gh);
out:
      while (qx--)
            gfs2_glock_dq_uninit(&ghs[qx]);
      kfree(ghs);
      gfs2_log_flush(ip->i_gl->gl_sbd, ip->i_gl);
      return error;
}

static int do_glock(struct gfs2_quota_data *qd, int force_refresh,
                struct gfs2_holder *q_gh)
{
      struct gfs2_sbd *sdp = qd->qd_gl->gl_sbd;
      struct gfs2_inode *ip = GFS2_I(sdp->sd_quota_inode);
      struct gfs2_holder i_gh;
      struct gfs2_quota_host q;
      char buf[sizeof(struct gfs2_quota)];
      struct file_ra_state ra_state;
      int error;
      struct gfs2_quota_lvb *qlvb;

      file_ra_state_init(&ra_state, sdp->sd_quota_inode->i_mapping);
restart:
      error = gfs2_glock_nq_init(qd->qd_gl, LM_ST_SHARED, 0, q_gh);
      if (error)
            return error;

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

      if (force_refresh || qd->qd_qb.qb_magic != cpu_to_be32(GFS2_MAGIC)) {
            loff_t pos;
            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;

            memset(buf, 0, sizeof(struct gfs2_quota));
            pos = qd2offset(qd);
            error = gfs2_internal_read(ip, &ra_state, buf,
                                 &pos, sizeof(struct gfs2_quota));
            if (error < 0)
                  goto fail_gunlock;

            gfs2_glock_dq_uninit(&i_gh);


            gfs2_quota_in(&q, buf);
            qlvb = (struct gfs2_quota_lvb *)qd->qd_gl->gl_lvb;
            qlvb->qb_magic = cpu_to_be32(GFS2_MAGIC);
            qlvb->__pad = 0;
            qlvb->qb_limit = cpu_to_be64(q.qu_limit);
            qlvb->qb_warn = cpu_to_be64(q.qu_warn);
            qlvb->qb_value = cpu_to_be64(q.qu_value);
            qd->qd_qb = *qlvb;

            if (gfs2_glock_is_blocking(qd->qd_gl)) {
                  gfs2_glock_dq_uninit(q_gh);
                  force_refresh = 0;
                  goto restart;
            }
      }

      return 0;

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

int gfs2_quota_lock(struct gfs2_inode *ip, u32 uid, u32 gid)
{
      struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
      struct gfs2_alloc *al = &ip->i_alloc;
      unsigned int x;
      int error = 0;

      gfs2_quota_hold(ip, uid, gid);

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

      sort(al->al_qd, al->al_qd_num, sizeof(struct gfs2_quota_data *),
           sort_qd, NULL);

      for (x = 0; x < al->al_qd_num; x++) {
            error = do_glock(al->al_qd[x], NO_FORCE, &al->al_qd_ghs[x]);
            if (error)
                  break;
      }

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

      return error;
}

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

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

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

      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;
            do_div(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_alloc *al = &ip->i_alloc;
      struct gfs2_quota_data *qda[4];
      unsigned int count = 0;
      unsigned int x;

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

      for (x = 0; x < al->al_qd_num; x++) {
            struct gfs2_quota_data *qd;
            int sync;

            qd = al->al_qd[x];
            sync = need_sync(qd);

            gfs2_glock_dq_uninit(&al->al_qd_ghs[x]);

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

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

out:
      gfs2_quota_unhold(ip);
}

#define MAX_LINE 256

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

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

      return 0;
}

int gfs2_quota_check(struct gfs2_inode *ip, u32 uid, u32 gid)
{
      struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
      struct gfs2_alloc *al = &ip->i_alloc;
      struct gfs2_quota_data *qd;
      s64 value;
      unsigned int x;
      int error = 0;

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

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

      for (x = 0; x < al->al_qd_num; x++) {
            qd = al->al_qd[x];

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

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

            if (be64_to_cpu(qd->qd_qb.qb_limit) && (s64)be64_to_cpu(qd->qd_qb.qb_limit) < value) {
                  print_message(qd, "exceeded");
                  error = -EDQUOT;
                  break;
            } else if (be64_to_cpu(qd->qd_qb.qb_warn) &&
                     (s64)be64_to_cpu(qd->qd_qb.qb_warn) < value &&
                     time_after_eq(jiffies, qd->qd_last_warn +
                               gfs2_tune_get(sdp,
                                    gt_quota_warn_period) * HZ)) {
                  error = print_message(qd, "warning");
                  qd->qd_last_warn = jiffies;
            }
      }

      return error;
}

void gfs2_quota_change(struct gfs2_inode *ip, s64 change,
                   u32 uid, u32 gid)
{
      struct gfs2_alloc *al = &ip->i_alloc;
      struct gfs2_quota_data *qd;
      unsigned int x;
      unsigned int found = 0;

      if (gfs2_assert_warn(GFS2_SB(&ip->i_inode), change))
            return;
      if (ip->i_di.di_flags & GFS2_DIF_SYSTEM)
            return;

      for (x = 0; x < al->al_qd_num; x++) {
            qd = al->al_qd[x];

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

int gfs2_quota_sync(struct gfs2_sbd *sdp)
{
      struct gfs2_quota_data **qda;
      unsigned int max_qd = gfs2_tune_get(sdp, gt_quota_simul_sync);
      unsigned int num_qd;
      unsigned int x;
      int error = 0;

      sdp->sd_quota_sync_gen++;

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

      do {
            num_qd = 0;

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

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

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

      kfree(qda);

      return error;
}

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

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

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

      qd_put(qd);

      return error;
}

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

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

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

      if (!ip->i_di.di_size || ip->i_di.di_size > (64 << 20) ||
          ip->i_di.di_size & (sdp->sd_sb.sb_bsize - 1)) {
            gfs2_consist_inode(ip);
            return -EIO;
      }
      sdp->sd_quota_slots = blocks * sdp->sd_qc_per_block;
      sdp->sd_quota_chunks = DIV_ROUND_UP(sdp->sd_quota_slots, 8 * PAGE_SIZE);

      error = -ENOMEM;

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

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

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

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

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

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

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

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

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

                  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_scan(struct gfs2_sbd *sdp)
{
      struct gfs2_quota_data *qd, *safe;
      LIST_HEAD(dead);

      spin_lock(&sdp->sd_quota_spin);
      list_for_each_entry_safe(qd, safe, &sdp->sd_quota_list, qd_list) {
            if (!qd->qd_count &&
                time_after_eq(jiffies, qd->qd_last_touched +
                          gfs2_tune_get(sdp, gt_quota_cache_secs) * HZ)) {
                  list_move(&qd->qd_list, &dead);
                  gfs2_assert_warn(sdp,
                               atomic_read(&sdp->sd_quota_count) > 0);
                  atomic_dec(&sdp->sd_quota_count);
            }
      }
      spin_unlock(&sdp->sd_quota_spin);

      while (!list_empty(&dead)) {
            qd = list_entry(dead.next, struct gfs2_quota_data, qd_list);
            list_del(&qd->qd_list);

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

            gfs2_lvb_unhold(qd->qd_gl);
            kfree(qd);
      }
}

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

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

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

            list_del(&qd->qd_list);
            atomic_dec(&sdp->sd_quota_count);
            spin_unlock(&sdp->sd_quota_spin);

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

            gfs2_lvb_unhold(qd->qd_gl);
            kfree(qd);

            spin_lock(&sdp->sd_quota_spin);
      }
      spin_unlock(&sdp->sd_quota_spin);

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

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


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