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quota.c

/******************************************************************************
*******************************************************************************
**
**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
**  Copyright (C) 2004 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 v.2.
**
*******************************************************************************
******************************************************************************/

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/smp_lock.h>
#include <linux/spinlock.h>
#include <asm/semaphore.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/tty.h>

#include "gfs.h"
#include "bmap.h"
#include "file.h"
#include "glock.h"
#include "glops.h"
#include "log.h"
#include "quota.h"
#include "rgrp.h"
#include "super.h"
#include "trans.h"

/**
 * gfs_quota_get - Get a structure to represent a quota change
 * @sdp: the filesystem
 * @user: TRUE if this is a user quota
 * @id: the uid or gid
 * @create: if TRUE, create the structure, otherwise return NULL
 * @qdp: the returned quota structure
 *
 * Returns: errno
 */

int
gfs_quota_get(struct gfs_sbd *sdp, int user, uint32_t id, int create,
            struct gfs_quota_data **qdp)
{
      struct gfs_quota_data *qd = NULL, *new_qd = NULL;
      struct list_head *tmp, *head;
      int error;

      *qdp = NULL;

      for (;;) {
            spin_lock(&sdp->sd_quota_lock);

            for (head = &sdp->sd_quota_list, tmp = head->next;
                 tmp != head;
                 tmp = tmp->next) {
                  qd = list_entry(tmp, struct gfs_quota_data, qd_list);
                  if (qd->qd_id == id &&
                      !test_bit(QDF_USER, &qd->qd_flags) == !user) {
                        qd->qd_count++;
                        break;
                  }
            }

            if (tmp == head)
                  qd = NULL;

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

            spin_unlock(&sdp->sd_quota_lock);

            if (qd || !create) {
                  if (new_qd) {
                        gfs_lvb_unhold(new_qd->qd_gl);
                        kfree(new_qd);
                        atomic_dec(&sdp->sd_quota_count);
                  }
                  *qdp = qd;
                  return 0;
            }

            new_qd = kmalloc(sizeof(struct gfs_quota_data), GFP_KERNEL);
            if (!new_qd)
                  return -ENOMEM;
            memset(new_qd, 0, sizeof(struct gfs_quota_data));

            new_qd->qd_count = 1;

            new_qd->qd_id = id;
            if (user)
                  set_bit(QDF_USER, &new_qd->qd_flags);

            INIT_LIST_HEAD(&new_qd->qd_le_list);

            error = gfs_glock_get(sdp, 2 * (uint64_t)id + ((user) ? 0 : 1),
                              &gfs_quota_glops, CREATE,
                              &new_qd->qd_gl);
            if (error) {
                  kfree(new_qd);
                  return error;
            }

            error = gfs_lvb_hold(new_qd->qd_gl);

            gfs_glock_put(new_qd->qd_gl);

            if (error) {
                  kfree(new_qd);
                  return error;
            }

            atomic_inc(&sdp->sd_quota_count);
      }
}

/**
 * gfs_quota_hold - increment the usage count on a struct gfs_quota_data
 * @sdp: the filesystem
 * @qd: the structure
 *
 */

void
gfs_quota_hold(struct gfs_sbd *sdp, struct gfs_quota_data *qd)
{
      spin_lock(&sdp->sd_quota_lock);
      gfs_assert(sdp, qd->qd_count,);
      qd->qd_count++;
      spin_unlock(&sdp->sd_quota_lock);
}

/**
 * gfs_quota_put - decrement the usage count on a struct gfs_quota_data
 * @sdp: the filesystem
 * @qd: the structure
 *
 * Free the structure if its reference count hits zero.
 *
 */

void
gfs_quota_put(struct gfs_sbd *sdp, struct gfs_quota_data *qd)
{
      spin_lock(&sdp->sd_quota_lock);
      gfs_assert(sdp, qd->qd_count,);
      qd->qd_count--;
      spin_unlock(&sdp->sd_quota_lock);
}

/**
 * quota_find - Find a quota change to sync to the quota file
 * @sdp: the filesystem
 *
 * The returned structure is locked and needs to be unlocked
 * with quota_unlock().
 *
 * Returns: A quota structure, or NULL
 */

static struct gfs_quota_data *
quota_find(struct gfs_sbd *sdp)
{
      struct list_head *tmp, *head;
      struct gfs_quota_data *qd = NULL;

      if (test_bit(SDF_ROFS, &sdp->sd_flags))
            return NULL;

      gfs_log_lock(sdp);
      spin_lock(&sdp->sd_quota_lock);

      if (!atomic_read(&sdp->sd_quota_od_count))
            goto out;

      for (head = &sdp->sd_quota_list, tmp = head->next;
           tmp != head;
           tmp = tmp->next) {
            qd = list_entry(tmp, struct gfs_quota_data, qd_list);

            if (test_bit(QDF_LOCK, &qd->qd_flags))
                  continue;
            if (!test_bit(QDF_OD_LIST, &qd->qd_flags))
                  continue;
            if (qd->qd_sync_gen >= sdp->sd_quota_sync_gen)
                  continue;

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

            set_bit(QDF_LOCK, &qd->qd_flags);
            qd->qd_count++;
            qd->qd_change_sync = qd->qd_change_od;

            goto out;
      }

      qd = NULL;

 out:
      spin_unlock(&sdp->sd_quota_lock);
      gfs_log_unlock(sdp);

      return qd;
}

/**
 * quota_trylock - Try to lock a given quota entry
 * @sdp: the filesystem
 * @qd: the quota data structure
 *
 * Returns: TRUE if the lock was successful, FALSE, otherwise
 */

static int
quota_trylock(struct gfs_sbd *sdp, struct gfs_quota_data *qd)
{
      int ret = FALSE;

      if (test_bit(SDF_ROFS, &sdp->sd_flags))
            return FALSE;

      gfs_log_lock(sdp);
      spin_lock(&sdp->sd_quota_lock);

      if (test_bit(QDF_LOCK, &qd->qd_flags))
            goto out;
      if (!test_bit(QDF_OD_LIST, &qd->qd_flags))
            goto out;

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

      set_bit(QDF_LOCK, &qd->qd_flags);
      qd->qd_count++;
      qd->qd_change_sync = qd->qd_change_od;

      ret = TRUE;

 out:
      spin_unlock(&sdp->sd_quota_lock);
      gfs_log_unlock(sdp);

      return ret;
}

/**
 * quota_unlock - drop and a reference on a quota structure
 * @sdp: the filesystem
 * @qd: the quota inode structure
 *
 */

static void
quota_unlock(struct gfs_sbd *sdp, struct gfs_quota_data *qd)
{
      spin_lock(&sdp->sd_quota_lock);

      gfs_assert_warn(sdp, test_bit(QDF_LOCK, &qd->qd_flags));
      clear_bit(QDF_LOCK, &qd->qd_flags);

      gfs_assert(sdp, qd->qd_count,);
      qd->qd_count--;

      spin_unlock(&sdp->sd_quota_lock);
}

/**
 * gfs_quota_merge - add/remove a quota change from the in-memory list
 * @sdp: the filesystem
 * @tag: the quota change tag
 *
 * Returns: errno
 */

int
gfs_quota_merge(struct gfs_sbd *sdp, struct gfs_quota_tag *tag)
{
      struct gfs_quota_data *qd;
      int error;

      error = gfs_quota_get(sdp,
                        tag->qt_flags & GFS_QTF_USER, tag->qt_id,
                        CREATE, &qd);
      if (error)
            return error;

      gfs_assert(sdp, qd->qd_change_ic == qd->qd_change_od,);

      gfs_log_lock(sdp);

      qd->qd_change_ic += tag->qt_change;
      qd->qd_change_od += tag->qt_change;

      if (qd->qd_change_od) {
            if (!test_bit(QDF_OD_LIST, &qd->qd_flags)) {
                  gfs_quota_hold(sdp, qd);
                  set_bit(QDF_OD_LIST, &qd->qd_flags);
                  atomic_inc(&sdp->sd_quota_od_count);
            }
      } else {
            gfs_assert_warn(sdp, test_bit(QDF_OD_LIST, &qd->qd_flags));
            clear_bit(QDF_OD_LIST, &qd->qd_flags);
            gfs_quota_put(sdp, qd);
            gfs_assert(sdp, atomic_read(&sdp->sd_quota_od_count) > 0,);
            atomic_dec(&sdp->sd_quota_od_count);
      }

      gfs_log_unlock(sdp);

      gfs_quota_put(sdp, qd);

      return 0;
}

/**
 * gfs_quota_scan - Look for unused struct gfs_quota_data structures to throw away
 * @sdp: the filesystem
 *
 */

void
gfs_quota_scan(struct gfs_sbd *sdp)
{
      struct list_head *head, *tmp, *next;
      struct gfs_quota_data *qd;
      LIST_HEAD(dead);

      spin_lock(&sdp->sd_quota_lock);

      for (head = &sdp->sd_quota_list, tmp = head->next, next = tmp->next;
           tmp != head;
           tmp = next, next = next->next) {
            qd = list_entry(tmp, struct gfs_quota_data, qd_list);
            if (!qd->qd_count)
                  list_move(&qd->qd_list, &dead);
      }

      spin_unlock(&sdp->sd_quota_lock);

      while (!list_empty(&dead)) {
            qd = list_entry(dead.next, struct gfs_quota_data, qd_list);

            gfs_assert_warn(sdp, !qd->qd_count);
            gfs_assert_warn(sdp, !test_bit(QDF_OD_LIST, &qd->qd_flags) &&
                        !test_bit(QDF_LOCK, &qd->qd_flags));
            gfs_assert_warn(sdp, !qd->qd_change_new && !qd->qd_change_ic &&
                        !qd->qd_change_od);

            list_del(&qd->qd_list);
            gfs_lvb_unhold(qd->qd_gl);
            kfree(qd);
            atomic_dec(&sdp->sd_quota_count);
      }
}

/**
 * gfs_quota_cleanup - get rid of any extra struct gfs_quota_data structures
 * @sdp: the filesystem
 *
 */

void
gfs_quota_cleanup(struct gfs_sbd *sdp)
{
      struct gfs_quota_data *qd;

 restart:
      gfs_log_lock(sdp);

      spin_lock(&sdp->sd_quota_lock);

      while (!list_empty(&sdp->sd_quota_list)) {
            qd = list_entry(sdp->sd_quota_list.next,
                        struct gfs_quota_data,
                        qd_list);

            if (qd->qd_count > 1) {
                  spin_unlock(&sdp->sd_quota_lock);
                  gfs_log_unlock(sdp);
                  set_current_state(TASK_UNINTERRUPTIBLE);
                  schedule_timeout(HZ);
                  goto restart;

            } else if (qd->qd_count) {
                  gfs_assert_warn(sdp,
                              test_bit(QDF_OD_LIST, &qd->qd_flags) &&
                              !test_bit(QDF_LOCK, &qd->qd_flags));
                  gfs_assert_warn(sdp, qd->qd_change_od &&
                              qd->qd_change_od == qd->qd_change_ic);
                  gfs_assert_warn(sdp, !qd->qd_change_new);

                  list_del(&qd->qd_list);
                  atomic_dec(&sdp->sd_quota_od_count);

                  spin_unlock(&sdp->sd_quota_lock);
                  gfs_lvb_unhold(qd->qd_gl);
                  kfree(qd);
                  atomic_dec(&sdp->sd_quota_count);
                  spin_lock(&sdp->sd_quota_lock);

            } else {
                  gfs_assert_warn(sdp,
                              !test_bit(QDF_OD_LIST, &qd->qd_flags) &&
                              !test_bit(QDF_LOCK, &qd->qd_flags));
                  gfs_assert_warn(sdp, !qd->qd_change_new &&
                              !qd->qd_change_ic &&
                              !qd->qd_change_od);

                  list_del(&qd->qd_list);

                  spin_unlock(&sdp->sd_quota_lock);
                  gfs_lvb_unhold(qd->qd_gl);
                  kfree(qd);
                  atomic_dec(&sdp->sd_quota_count);
                  spin_lock(&sdp->sd_quota_lock);
            }
      }

      spin_unlock(&sdp->sd_quota_lock);

      gfs_assert(sdp, !atomic_read(&sdp->sd_quota_od_count),);

      gfs_log_unlock(sdp);
}

/**
 * sort_qd - figure out the order between two quota data structures
 * @a: first quota data structure
 * @b: second quota data structure
 *
 * Returns: -1 if @a comes before @b, 0 if @a equals @b, 1 if @b comes before @a
 */

static int
sort_qd(const void *a, const void *b)
{
      struct gfs_quota_data *qd_a = *(struct gfs_quota_data **)a;
      struct gfs_quota_data *qd_b = *(struct gfs_quota_data **)b;
      int ret = 0;

      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))
                  ret = -1;
            else
                  ret = 1;
      } else {
            if (qd_a->qd_id < qd_b->qd_id)
                  ret = -1;
            else if (qd_a->qd_id > qd_b->qd_id)
                  ret = 1;
      }

      return ret;
}

/**
 * do_quota_sync - Sync a bunch quota changes to the quota file
 * @sdp: the filesystem
 * @qda: an array of struct gfs_quota_data structures to be synced
 * @num_qd: the number of elements in @qda
 *
 * Returns: errno
 */

static int
do_quota_sync(struct gfs_sbd *sdp, struct gfs_quota_data **qda,
            unsigned int num_qd)
{
      struct gfs_inode *ip = sdp->sd_qinode;
      struct gfs_alloc *al = NULL;
      struct gfs_holder i_gh, *ghs;
      struct gfs_quota q;
      char buf[sizeof(struct gfs_quota)];
      uint64_t offset;
      unsigned int qx, x;
      int ar;
      unsigned int nalloc = 0;
      unsigned int data_blocks, ind_blocks;
      int error;

      gfs_write_calc_reserv(ip, sizeof(struct gfs_quota), &data_blocks,
                        &ind_blocks);

      ghs = kmalloc(num_qd * sizeof(struct gfs_holder), GFP_KERNEL);
      if (!ghs)
            return -ENOMEM;

      gfs_sort(qda, num_qd, sizeof (struct gfs_quota_data *), sort_qd);
      for (qx = 0; qx < num_qd; qx++) {
            error = gfs_glock_nq_init(qda[qx]->qd_gl,
                                LM_ST_EXCLUSIVE,
                                GL_NOCACHE, &ghs[qx]);
            if (error)
                  goto fail;
      }

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

      for (x = 0; x < num_qd; x++) {
            offset = (2 * (uint64_t)qda[x]->qd_id +
                    ((test_bit(QDF_USER, &qda[x]->qd_flags)) ? 0 : 1)) *
                  sizeof(struct gfs_quota);

            error = gfs_write_alloc_required(ip, offset,
                                     sizeof(struct gfs_quota),
                                     &ar);
            if (error)
                  goto fail_gunlock;

            if (ar)
                  nalloc++;
      }

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

            error =
                gfs_quota_hold_m(ip, NO_QUOTA_CHANGE,
                                 NO_QUOTA_CHANGE);
            if (error)
                  goto fail_alloc;

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

            error = gfs_inplace_reserve(ip);
            if (error)
                  goto fail_qs;

            /* Trans may require:
               two (journaled) data blocks, a dinode block, RG bitmaps to allocate from,
               indirect blocks, and a quota block */

            error = gfs_trans_begin(sdp,
                              1 + al->al_rgd->rd_ri.ri_length +
                              num_qd * data_blocks +
                              nalloc * ind_blocks,
                              gfs_struct2blk(sdp, num_qd + 2,
                                           sizeof(struct gfs_quota_tag)));
            if (error)
                  goto fail_ipres;
      } else {
            /* Trans may require:
               Data blocks, a dinode block, and quota blocks */

            error = gfs_trans_begin(sdp,
                              1 + data_blocks * num_qd,
                              gfs_struct2blk(sdp, num_qd,
                                           sizeof(struct gfs_quota_tag)));
            if (error)
                  goto fail_gunlock;
      }

      for (x = 0; x < num_qd; x++) {
            offset = (2 * (uint64_t)qda[x]->qd_id +
                    ((test_bit(QDF_USER, &qda[x]->qd_flags)) ? 0 : 1)) *
                  sizeof(struct gfs_quota);

            /*  The quota file may not be a multiple of sizeof(struct gfs_quota) bytes.  */
            memset(buf, 0, sizeof(struct gfs_quota));

            error = gfs_internal_read(ip, buf, offset,
                                sizeof(struct gfs_quota));
            if (error < 0)
                  goto fail_end_trans;

            gfs_quota_in(&q, buf);
            q.qu_value += qda[x]->qd_change_sync;
            gfs_quota_out(&q, buf);

            error = gfs_internal_write(ip, buf, offset,
                                 sizeof(struct gfs_quota));
            if (error < 0)
                  goto fail_end_trans;
            else if (error != sizeof(struct gfs_quota)) {
                  error = -EIO;
                  goto fail_end_trans;
            }

            if (test_bit(QDF_USER, &qda[x]->qd_flags))
                  gfs_trans_add_quota(sdp, -qda[x]->qd_change_sync,
                                  qda[x]->qd_id, NO_QUOTA_CHANGE);
            else
                  gfs_trans_add_quota(sdp, -qda[x]->qd_change_sync,
                                  NO_QUOTA_CHANGE, qda[x]->qd_id);

            memset(&qda[x]->qd_qb, 0, sizeof(struct gfs_quota_lvb));
            qda[x]->qd_qb.qb_magic = GFS_MAGIC;
            qda[x]->qd_qb.qb_limit = q.qu_limit;
            qda[x]->qd_qb.qb_warn = q.qu_warn;
            qda[x]->qd_qb.qb_value = q.qu_value;

            gfs_quota_lvb_out(&qda[x]->qd_qb, qda[x]->qd_gl->gl_lvb);
      }

      gfs_trans_end(sdp);

      if (nalloc) {
            gfs_assert_warn(sdp, al->al_alloced_meta);
            gfs_inplace_release(ip);
            gfs_quota_unhold_m(ip);
            gfs_alloc_put(ip);
      }

      gfs_glock_dq_uninit(&i_gh);

      for (x = 0; x < num_qd; x++)
            gfs_glock_dq_uninit(&ghs[x]);

      kfree(ghs);

      gfs_log_flush_glock(ip->i_gl);

      return 0;

 fail_end_trans:
      gfs_trans_end(sdp);

 fail_ipres:
      if (nalloc)
            gfs_inplace_release(ip);

 fail_qs:
      if (nalloc)
            gfs_quota_unhold_m(ip);

 fail_alloc:
      if (nalloc)
            gfs_alloc_put(ip);

 fail_gunlock:
      gfs_glock_dq_uninit(&i_gh);

 fail:
      while (qx--)
            gfs_glock_dq_uninit(&ghs[qx]);

      kfree(ghs);

      return error;
}

/**
 * glock_q - Acquire a lock for a quota entry
 * @sdp: the filesystem
 * @qd: the quota data structure to glock
 * @force_refresh: If TRUE, always read from the quota file
 * @q_gh: the glock holder for the quota lock
 *
 * Returns: errno
 */

static int
glock_q(struct gfs_sbd *sdp, struct gfs_quota_data *qd, int force_refresh,
      struct gfs_holder *q_gh)
{
      struct gfs_holder i_gh;
      struct gfs_quota q;
      char buf[sizeof(struct gfs_quota)];
      int error;

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

      gfs_quota_lvb_in(&qd->qd_qb, qd->qd_gl->gl_lvb);

      if (force_refresh ||
          qd->qd_qb.qb_magic != GFS_MAGIC) {
            gfs_glock_dq_uninit(q_gh);
            error = gfs_glock_nq_init(qd->qd_gl,
                                LM_ST_EXCLUSIVE, GL_NOCACHE,
                                q_gh);
            if (error)
                  return error;

            error = gfs_glock_nq_init(sdp->sd_qinode->i_gl,
                                LM_ST_SHARED, 0,
                                &i_gh);
            if (error)
                  goto fail;

            memset(buf, 0, sizeof(struct gfs_quota));

            error = gfs_internal_read(sdp->sd_qinode, buf,
                                (2 * (uint64_t)qd->qd_id +
                                 ((test_bit(QDF_USER, &qd->qd_flags)) ? 0 : 1)) *
                                sizeof(struct gfs_quota),
                                sizeof(struct gfs_quota));
            if (error < 0)
                  goto fail_gunlock;

            gfs_glock_dq_uninit(&i_gh);

            gfs_quota_in(&q, buf);

            memset(&qd->qd_qb, 0, sizeof(struct gfs_quota_lvb));
            qd->qd_qb.qb_magic = GFS_MAGIC;
            qd->qd_qb.qb_limit = q.qu_limit;
            qd->qd_qb.qb_warn = q.qu_warn;
            qd->qd_qb.qb_value = q.qu_value;

            gfs_quota_lvb_out(&qd->qd_qb, qd->qd_gl->gl_lvb);

            gfs_glock_dq_uninit(q_gh);
            force_refresh = FALSE;
            goto restart;
      }

      return 0;

 fail_gunlock:
      gfs_glock_dq_uninit(&i_gh);

 fail:
      gfs_glock_dq_uninit(q_gh);

      return error;
}

/**
 * gfs_quota_hold_m - Hold the quota structures for up to 4 IDs
 * @ip: Two of the IDs are the UID and GID from this file
 * @uid: a UID or the constant NO_QUOTA_CHANGE
 * @gid: a GID or the constant NO_QUOTA_CHANGE
 *
 * The struct gfs_quota_data structures representing the locks are
 * stored in the ip->i_alloc->al_qd array.
 * 
 * Returns:  errno
 */

int
gfs_quota_hold_m(struct gfs_inode *ip, uint32_t uid, uint32_t gid)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct gfs_alloc *al = ip->i_alloc;
      unsigned int x = 0;
      int error;

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

      if (!gfs_tune_get(sdp, gt_quota_account))
            return 0;

      error = gfs_quota_get(sdp, TRUE, ip->i_di.di_uid,
                        CREATE, &al->al_qd[x]);
      if (error)
            goto fail;
      x++;

      error = gfs_quota_get(sdp, FALSE, ip->i_di.di_gid,
                        CREATE, &al->al_qd[x]);
      if (error)
            goto fail;
      x++;

      if (uid != NO_QUOTA_CHANGE) {
            error = gfs_quota_get(sdp, TRUE, uid,
                              CREATE, &al->al_qd[x]);
            if (error)
                  goto fail;
            x++;
      }

      if (gid != NO_QUOTA_CHANGE) {
            error = gfs_quota_get(sdp, FALSE, gid,
                              CREATE, &al->al_qd[x]);
            if (error)
                  goto fail;
            x++;
      }

      al->al_qd_num = x;

      return 0;

 fail:
      if (x) {
            al->al_qd_num = x;
            gfs_quota_unhold_m(ip);
      }

      return error;
}

/**
 * gfs_quota_unhold_m - throw away some quota locks
 * @ip: the inode who's ip->i_alloc->al_qd array holds the structures
 *
 */

void
gfs_quota_unhold_m(struct gfs_inode *ip)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct gfs_alloc *al = ip->i_alloc;
      unsigned int x;

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

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

/**
 * gfs_quota_lock_m - Acquire the quota locks for up to 4 IDs
 * @ip: Two of the IDs are the UID and GID from this file
 * @uid: a UID or the constant NO_QUOTA_CHANGE
 * @gid: a GID or the constant NO_QUOTA_CHANGE
 *
 * The struct gfs_quota_data structures representing the locks are
 * stored in the ip->i_alloc->al_qd array.
 * 
 * Returns:  errno
 */

int
gfs_quota_lock_m(struct gfs_inode *ip, uint32_t uid, uint32_t gid)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct gfs_alloc *al = ip->i_alloc;
      unsigned int x;
      int error;

      gfs_quota_hold_m(ip, uid, gid);

      if (!gfs_tune_get(sdp, gt_quota_enforce))
            return 0;
      if (capable(CAP_SYS_RESOURCE))
            return 0;

      gfs_sort(al->al_qd, al->al_qd_num,
             sizeof(struct gfs_quota_data *), sort_qd);

      for (x = 0; x < al->al_qd_num; x++) {
            error = glock_q(sdp, al->al_qd[x], FALSE, &al->al_qd_ghs[x]);
            if (error)
                  goto fail;
      }

      set_bit(GIF_QD_LOCKED, &ip->i_flags);

      return 0;

      fail:
      while (x--)
            gfs_glock_dq_uninit(&al->al_qd_ghs[x]);

      return error;
}

/**
 * gfs_quota_unlock_m - drop some quota locks
 * @ip: the inode who's ip->i_alloc->al_qd array holds the locks
 *
 */

void
gfs_quota_unlock_m(struct gfs_inode *ip)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct gfs_alloc *al = ip->i_alloc;
      struct gfs_quota_data *qd, *qda[4];
      int64_t value;
      unsigned int count = 0;
      unsigned int x;
      int do_sync;

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

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

            spin_lock(&sdp->sd_quota_lock);
            value = qd->qd_change_new + qd->qd_change_ic;
            spin_unlock(&sdp->sd_quota_lock);

            do_sync = TRUE;
            if (!qd->qd_qb.qb_limit)
                  do_sync = FALSE;
            else if (qd->qd_qb.qb_value >= (int64_t)qd->qd_qb.qb_limit)
                  do_sync = FALSE;
            else {
                  struct gfs_tune *gt = &sdp->sd_tune;
                  unsigned int num, den;
                  int64_t v;

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

                  v = value * gfs_num_journals(sdp) * num;
                  do_div(v, den);
                  v += qd->qd_qb.qb_value;
                  if (v < (int64_t)qd->qd_qb.qb_limit)
                        do_sync = FALSE;
            }

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

            if (do_sync) {
                  gfs_log_flush(sdp);
                  if (quota_trylock(sdp, qd))
                        qda[count++] = qd;
            }
      }

      if (count) {
            do_quota_sync(sdp, qda, count);

            for (x = 0; x < count; x++)
                  quota_unlock(sdp, qda[x]);
      }

 out:
      gfs_quota_unhold_m(ip);
}

/**
 * print_quota_message - print a message to the user's tty about quotas
 * @sdp: the filesystem
 * @qd: the quota ID that the message is about
 * @type: the type of message ("exceeded" or "warning")
 *
 * Returns: errno
 */

static int
print_quota_message(struct gfs_sbd *sdp, struct gfs_quota_data *qd, char *type)
{
      struct tty_struct *tty;
      char *line;
      int len;

      line = kmalloc(256, GFP_KERNEL);
      if (!line)
            return -ENOMEM;

      len = snprintf(line, 256, "GFS: 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);

      if (current->signal) {
            tty = current->signal->tty;
            if (tty && tty->driver->write)
                  tty->driver->write(tty, line, len);
      }

      kfree(line);

      return 0;
}

/**
 * gfs_quota_check - Check to see if a block allocation is possible
 * @ip: the inode who's ip->i_res.ir_qd array holds the quota locks
 * @uid: the UID the block is allocated for
 * @gid: the GID the block is allocated for
 *
 */

int
gfs_quota_check(struct gfs_inode *ip, uint32_t uid, uint32_t gid)
{
      struct gfs_sbd *sdp = ip->i_sbd;
      struct gfs_alloc *al = ip->i_alloc;
      struct gfs_quota_data *qd;
      int64_t value;
      unsigned int x;
      int error = 0;

      if (!al)
            return 0;

      if (!gfs_tune_get(sdp, gt_quota_enforce))
            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;

            spin_lock(&sdp->sd_quota_lock);
            value = qd->qd_change_new + qd->qd_change_ic;
            spin_unlock(&sdp->sd_quota_lock);
            value += qd->qd_qb.qb_value;

            if (qd->qd_qb.qb_limit && (int64_t)qd->qd_qb.qb_limit < value) {
                  print_quota_message(sdp, qd, "exceeded");
                  error = -EDQUOT;
                  break;
            } else if (qd->qd_qb.qb_warn &&
                     (int64_t)qd->qd_qb.qb_warn < value &&
                     time_after_eq(jiffies,
                               qd->qd_last_warn +
                               gfs_tune_get(sdp, gt_quota_warn_period) * HZ)) {
                  error = print_quota_message(sdp, qd, "warning");
                  qd->qd_last_warn = jiffies;
            }
      }

      return error;
}

/**
 * gfs_quota_sync - Sync quota changes to the quota file
 * @sdp: the filesystem
 *
 * Returns: errno
 */

int
gfs_quota_sync(struct gfs_sbd *sdp)
{
      struct gfs_quota_data **qda;
      unsigned int max_qd = gfs_tune_get(sdp, gt_quota_simul_sync);
      unsigned int num_qd;
      unsigned int x;
      int error = 0;

      sdp->sd_quota_sync_gen++;

      qda = kmalloc(max_qd * sizeof(struct gfs_quota_data *), GFP_KERNEL);
      if (!qda)
            return -ENOMEM;
      memset(qda, 0, max_qd * sizeof(struct gfs_quota_data *));

      do {
            num_qd = 0;

            for (;;) {
                  qda[num_qd] = quota_find(sdp);
                  if (!qda[num_qd])
                        break;

                  if (++num_qd == max_qd)
                        break;
            }

            if (num_qd) {
                  error = do_quota_sync(sdp, qda, num_qd);
                  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++)
                        quota_unlock(sdp, qda[x]);
            }
      }
      while (!error && num_qd == max_qd);

      kfree(qda);

      return error;
}

/**
 * gfs_quota_refresh - Refresh the LVB for a given quota ID
 * @sdp: the filesystem
 * @user:
 * @id:
 *
 * Returns: errno
 */

int
gfs_quota_refresh(struct gfs_sbd *sdp, int user, uint32_t id)
{
      struct gfs_quota_data *qd;
      struct gfs_holder q_gh;
      int error;

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

      error = glock_q(sdp, qd, TRUE, &q_gh);
      if (!error)
            gfs_glock_dq_uninit(&q_gh);

      gfs_quota_put(sdp, qd);

      return error;
}

/**
 * gfs_quota_read - Read the info a given quota ID
 * @sdp: the filesystem
 * @user:
 * @id:
 * @q:
 *
 * Returns: errno
 */

int
gfs_quota_read(struct gfs_sbd *sdp, int user, uint32_t id,
             struct gfs_quota *q)
{
      struct gfs_quota_data *qd;
      struct gfs_holder q_gh;
      int error;

      if (((user) ? (id != current->fsuid) : (!in_group_p(id))) &&
          !capable(CAP_SYS_ADMIN))
            return -EACCES;

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

      error = glock_q(sdp, qd, FALSE, &q_gh);
      if (error)
            goto out;

      memset(q, 0, sizeof(struct gfs_quota));
      q->qu_limit = qd->qd_qb.qb_limit;
      q->qu_warn = qd->qd_qb.qb_warn;
      q->qu_value = qd->qd_qb.qb_value;

      spin_lock(&sdp->sd_quota_lock);
      q->qu_value += qd->qd_change_new + qd->qd_change_ic;
      spin_unlock(&sdp->sd_quota_lock);

      gfs_glock_dq_uninit(&q_gh);

 out:
      gfs_quota_put(sdp, qd);

      return error;
}

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