/*
   * Implementation of the diskquota system for the LINUX operating system. QUOTA
   * is implemented using the BSD system call interface as the means of
   * communication with the user level. This file contains the generic routines
   * called by the different filesystems on allocation of an inode or block.
   * These routines take care of the administration needed to have a consistent
   * diskquota tracking system. The ideas of both user and group quotas are based
   * on the Melbourne quota system as used on BSD derived systems. The internal
   * implementation is based on one of the several variants of the LINUX
   * inode-subsystem with added complexity of the diskquota system.
   * 

   * Author:	Marco van Wieringen <mvw@planets.elm.net>
   *
   * Fixes:   Dmitry Gorodchanin <pgmdsg@ibi.com>, 11 Feb 96
   *
   *		Revised list management to avoid races
   *		-- Bill Hawes, <whawes@star.net>, 9/98
   *
   *		Fixed races in dquot_transfer(), dqget() and dquot_alloc_...().
   *		As the consequence the locking was moved from dquot_decr_...(),
   *		dquot_incr_...() to calling functions.
   *		invalidate_dquots() now writes modified dquots.
   *		Serialized quota_off() and quota_on() for mount point.
   *		Fixed a few bugs in grow_dquots().
   *		Fixed deadlock in write_dquot() - we no longer account quotas on
   *		quota files
   *		remove_dquot_ref() moved to inode.c - it now traverses through inodes
   *		add_dquot_ref() restarts after blocking
   *		Added check for bogus uid and fixed check for group in quotactl.
   *		Jan Kara, <jack@suse.cz>, sponsored by SuSE CR, 10-11/99
   *
   *		Used struct list_head instead of own list struct
   *		Invalidation of referenced dquots is no longer possible
   *		Improved free_dquots list management
   *		Quota and i_blocks are now updated in one place to avoid races
   *		Warnings are now delayed so we won't block in critical section
   *		Write updated not to require dquot lock
   *		Jan Kara, <jack@suse.cz>, 9/2000
   *
   *		Added dynamic quota structure allocation
   *		Jan Kara <jack@suse.cz> 12/2000
   *
   *		Rewritten quota interface. Implemented new quota format and
   *		formats registering.
   *		Jan Kara, <jack@suse.cz>, 2001,2002
   *
   *		New SMP locking.
   *		Jan Kara, <jack@suse.cz>, 10/2002
   *
   *		Added journalled quota support, fix lock inversion problems
   *		Jan Kara, <jack@suse.cz>, 2003,2004
   *
   * (C) Copyright 1994 - 1997 Marco van Wieringen 
   */
  
  #include <linux/errno.h>
  #include <linux/kernel.h>
  #include <linux/fs.h>
  #include <linux/mount.h>
  #include <linux/mm.h>
  #include <linux/time.h>
  #include <linux/types.h>
  #include <linux/string.h>
  #include <linux/fcntl.h>
  #include <linux/stat.h>
  #include <linux/tty.h>
  #include <linux/file.h>
  #include <linux/slab.h>
  #include <linux/sysctl.h>

  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/proc_fs.h>
  #include <linux/security.h>
  #include <linux/kmod.h>
  #include <linux/namei.h>
  #include <linux/buffer_head.h>

  #include <linux/capability.h>

  #include <linux/quotaops.h>

  #include <linux/writeback.h> /* for inode_lock, oddly enough.. */

  #ifdef CONFIG_QUOTA_NETLINK_INTERFACE
  #include <net/netlink.h>
  #include <net/genetlink.h>
  #endif

  
  #include <asm/uaccess.h>
  
  #define __DQUOT_PARANOIA
  
  /*

   * There are three quota SMP locks. dq_list_lock protects all lists with quotas
   * and quota formats, dqstats structure containing statistics about the lists
   * dq_data_lock protects data from dq_dqb and also mem_dqinfo structures and
   * also guards consistency of dquot->dq_dqb with inode->i_blocks, i_bytes.

   * i_blocks and i_bytes updates itself are guarded by i_lock acquired directly

   * in inode_add_bytes() and inode_sub_bytes(). dq_state_lock protects
   * modifications of quota state (on quotaon and quotaoff) and readers who care
   * about latest values take it as well.

   *

   * The spinlock ordering is hence: dq_data_lock > dq_list_lock > i_lock,
   *   dq_list_lock > dq_state_lock

   *
   * Note that some things (eg. sb pointer, type, id) doesn't change during
   * the life of the dquot structure and so needn't to be protected by a lock
   *
   * Any operation working on dquots via inode pointers must hold dqptr_sem.  If
   * operation is just reading pointers from inode (or not using them at all) the
   * read lock is enough. If pointers are altered function must hold write lock
   * (these locking rules also apply for S_NOQUOTA flag in the inode - note that

   * for altering the flag i_mutex is also needed).

   *

   * Each dquot has its dq_lock mutex. Locked dquots might not be referenced

   * from inodes (dquot_alloc_space() and such don't check the dq_lock).
   * Currently dquot is locked only when it is being read to memory (or space for
   * it is being allocated) on the first dqget() and when it is being released on
   * the last dqput(). The allocation and release oparations are serialized by
   * the dq_lock and by checking the use count in dquot_release().  Write
   * operations on dquots don't hold dq_lock as they copy data under dq_data_lock
   * spinlock to internal buffers before writing.
   *
   * Lock ordering (including related VFS locks) is the following:

   *   i_mutex > dqonoff_sem > journal_lock > dqptr_sem > dquot->dq_lock >
   *   dqio_mutex

   * The lock ordering of dqptr_sem imposed by quota code is only dqonoff_sem >
   * dqptr_sem. But filesystem has to count with the fact that functions such as
   * dquot_alloc_space() acquire dqptr_sem and they usually have to be called
   * from inside a transaction to keep filesystem consistency after a crash. Also
   * filesystems usually want to do some IO on dquot from ->mark_dirty which is
   * called with dqptr_sem held.

   * i_mutex on quota files is special (it's below dqio_mutex)

   */
  
  static DEFINE_SPINLOCK(dq_list_lock);

  static DEFINE_SPINLOCK(dq_state_lock);

  DEFINE_SPINLOCK(dq_data_lock);
  
  static char *quotatypes[] = INITQFNAMES;
  static struct quota_format_type *quota_formats;	/* List of registered formats */
  static struct quota_module_name module_names[] = INIT_QUOTA_MODULE_NAMES;
  
  /* SLAB cache for dquot structures */

  static struct kmem_cache *dquot_cachep;

  
  int register_quota_format(struct quota_format_type *fmt)
  {
  	spin_lock(&dq_list_lock);
  	fmt->qf_next = quota_formats;
  	quota_formats = fmt;
  	spin_unlock(&dq_list_lock);
  	return 0;
  }
  
  void unregister_quota_format(struct quota_format_type *fmt)
  {
  	struct quota_format_type **actqf;
  
  	spin_lock(&dq_list_lock);
  	for (actqf = &quota_formats; *actqf && *actqf != fmt; actqf = &(*actqf)->qf_next);
  	if (*actqf)
  		*actqf = (*actqf)->qf_next;
  	spin_unlock(&dq_list_lock);
  }
  
  static struct quota_format_type *find_quota_format(int id)
  {
  	struct quota_format_type *actqf;
  
  	spin_lock(&dq_list_lock);
  	for (actqf = quota_formats; actqf && actqf->qf_fmt_id != id; actqf = actqf->qf_next);
  	if (!actqf || !try_module_get(actqf->qf_owner)) {
  		int qm;
  
  		spin_unlock(&dq_list_lock);
  		
  		for (qm = 0; module_names[qm].qm_fmt_id && module_names[qm].qm_fmt_id != id; qm++);
  		if (!module_names[qm].qm_fmt_id || request_module(module_names[qm].qm_mod_name))
  			return NULL;
  
  		spin_lock(&dq_list_lock);
  		for (actqf = quota_formats; actqf && actqf->qf_fmt_id != id; actqf = actqf->qf_next);
  		if (actqf && !try_module_get(actqf->qf_owner))
  			actqf = NULL;
  	}
  	spin_unlock(&dq_list_lock);
  	return actqf;
  }
  
  static void put_quota_format(struct quota_format_type *fmt)
  {
  	module_put(fmt->qf_owner);
  }
  
  /*
   * Dquot List Management:
   * The quota code uses three lists for dquot management: the inuse_list,
   * free_dquots, and dquot_hash[] array. A single dquot structure may be
   * on all three lists, depending on its current state.
   *
   * All dquots are placed to the end of inuse_list when first created, and this
   * list is used for invalidate operation, which must look at every dquot.
   *
   * Unused dquots (dq_count == 0) are added to the free_dquots list when freed,
   * and this list is searched whenever we need an available dquot.  Dquots are
   * removed from the list as soon as they are used again, and
   * dqstats.free_dquots gives the number of dquots on the list. When
   * dquot is invalidated it's completely released from memory.
   *
   * Dquots with a specific identity (device, type and id) are placed on
   * one of the dquot_hash[] hash chains. The provides an efficient search
   * mechanism to locate a specific dquot.
   */
  
  static LIST_HEAD(inuse_list);
  static LIST_HEAD(free_dquots);
  static unsigned int dq_hash_bits, dq_hash_mask;
  static struct hlist_head *dquot_hash;
  
  struct dqstats dqstats;

  static inline unsigned int
  hashfn(const struct super_block *sb, unsigned int id, int type)
  {
  	unsigned long tmp;
  
  	tmp = (((unsigned long)sb>>L1_CACHE_SHIFT) ^ id) * (MAXQUOTAS - type);
  	return (tmp + (tmp >> dq_hash_bits)) & dq_hash_mask;
  }
  
  /*
   * Following list functions expect dq_list_lock to be held
   */
  static inline void insert_dquot_hash(struct dquot *dquot)
  {
  	struct hlist_head *head = dquot_hash + hashfn(dquot->dq_sb, dquot->dq_id, dquot->dq_type);
  	hlist_add_head(&dquot->dq_hash, head);
  }
  
  static inline void remove_dquot_hash(struct dquot *dquot)
  {
  	hlist_del_init(&dquot->dq_hash);
  }
  
  static inline struct dquot *find_dquot(unsigned int hashent, struct super_block *sb, unsigned int id, int type)
  {
  	struct hlist_node *node;
  	struct dquot *dquot;
  
  	hlist_for_each (node, dquot_hash+hashent) {
  		dquot = hlist_entry(node, struct dquot, dq_hash);
  		if (dquot->dq_sb == sb && dquot->dq_id == id && dquot->dq_type == type)
  			return dquot;
  	}
  	return NODQUOT;
  }
  
  /* Add a dquot to the tail of the free list */
  static inline void put_dquot_last(struct dquot *dquot)
  {

  	list_add_tail(&dquot->dq_free, &free_dquots);

  	dqstats.free_dquots++;
  }
  
  static inline void remove_free_dquot(struct dquot *dquot)
  {
  	if (list_empty(&dquot->dq_free))
  		return;
  	list_del_init(&dquot->dq_free);
  	dqstats.free_dquots--;
  }
  
  static inline void put_inuse(struct dquot *dquot)
  {
  	/* We add to the back of inuse list so we don't have to restart
  	 * when traversing this list and we block */

  	list_add_tail(&dquot->dq_inuse, &inuse_list);

  	dqstats.allocated_dquots++;
  }
  
  static inline void remove_inuse(struct dquot *dquot)
  {
  	dqstats.allocated_dquots--;
  	list_del(&dquot->dq_inuse);
  }
  /*
   * End of list functions needing dq_list_lock
   */
  
  static void wait_on_dquot(struct dquot *dquot)
  {

  	mutex_lock(&dquot->dq_lock);
  	mutex_unlock(&dquot->dq_lock);

  }

  static inline int dquot_dirty(struct dquot *dquot)
  {
  	return test_bit(DQ_MOD_B, &dquot->dq_flags);
  }
  
  static inline int mark_dquot_dirty(struct dquot *dquot)
  {
  	return dquot->dq_sb->dq_op->mark_dirty(dquot);
  }

  
  int dquot_mark_dquot_dirty(struct dquot *dquot)
  {
  	spin_lock(&dq_list_lock);
  	if (!test_and_set_bit(DQ_MOD_B, &dquot->dq_flags))
  		list_add(&dquot->dq_dirty, &sb_dqopt(dquot->dq_sb)->
  				info[dquot->dq_type].dqi_dirty_list);
  	spin_unlock(&dq_list_lock);
  	return 0;
  }
  
  /* This function needs dq_list_lock */
  static inline int clear_dquot_dirty(struct dquot *dquot)
  {
  	if (!test_and_clear_bit(DQ_MOD_B, &dquot->dq_flags))
  		return 0;
  	list_del_init(&dquot->dq_dirty);
  	return 1;
  }
  
  void mark_info_dirty(struct super_block *sb, int type)
  {
  	set_bit(DQF_INFO_DIRTY_B, &sb_dqopt(sb)->info[type].dqi_flags);
  }
  EXPORT_SYMBOL(mark_info_dirty);
  
  /*
   *	Read dquot from disk and alloc space for it
   */
  
  int dquot_acquire(struct dquot *dquot)
  {
  	int ret = 0, ret2 = 0;
  	struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);

  	mutex_lock(&dquot->dq_lock);
  	mutex_lock(&dqopt->dqio_mutex);

  	if (!test_bit(DQ_READ_B, &dquot->dq_flags))
  		ret = dqopt->ops[dquot->dq_type]->read_dqblk(dquot);
  	if (ret < 0)
  		goto out_iolock;
  	set_bit(DQ_READ_B, &dquot->dq_flags);
  	/* Instantiate dquot if needed */
  	if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && !dquot->dq_off) {
  		ret = dqopt->ops[dquot->dq_type]->commit_dqblk(dquot);
  		/* Write the info if needed */
  		if (info_dirty(&dqopt->info[dquot->dq_type]))
  			ret2 = dqopt->ops[dquot->dq_type]->write_file_info(dquot->dq_sb, dquot->dq_type);
  		if (ret < 0)
  			goto out_iolock;
  		if (ret2 < 0) {
  			ret = ret2;
  			goto out_iolock;
  		}
  	}
  	set_bit(DQ_ACTIVE_B, &dquot->dq_flags);
  out_iolock:

  	mutex_unlock(&dqopt->dqio_mutex);
  	mutex_unlock(&dquot->dq_lock);

  	return ret;
  }
  
  /*
   *	Write dquot to disk
   */
  int dquot_commit(struct dquot *dquot)
  {
  	int ret = 0, ret2 = 0;
  	struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);

  	mutex_lock(&dqopt->dqio_mutex);

  	spin_lock(&dq_list_lock);
  	if (!clear_dquot_dirty(dquot)) {
  		spin_unlock(&dq_list_lock);
  		goto out_sem;
  	}
  	spin_unlock(&dq_list_lock);
  	/* Inactive dquot can be only if there was error during read/init
  	 * => we have better not writing it */
  	if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
  		ret = dqopt->ops[dquot->dq_type]->commit_dqblk(dquot);
  		if (info_dirty(&dqopt->info[dquot->dq_type]))
  			ret2 = dqopt->ops[dquot->dq_type]->write_file_info(dquot->dq_sb, dquot->dq_type);
  		if (ret >= 0)
  			ret = ret2;
  	}
  out_sem:

  	mutex_unlock(&dqopt->dqio_mutex);

  	return ret;
  }
  
  /*
   *	Release dquot
   */
  int dquot_release(struct dquot *dquot)
  {
  	int ret = 0, ret2 = 0;
  	struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);

  	mutex_lock(&dquot->dq_lock);

  	/* Check whether we are not racing with some other dqget() */
  	if (atomic_read(&dquot->dq_count) > 1)
  		goto out_dqlock;

  	mutex_lock(&dqopt->dqio_mutex);

  	if (dqopt->ops[dquot->dq_type]->release_dqblk) {
  		ret = dqopt->ops[dquot->dq_type]->release_dqblk(dquot);
  		/* Write the info */
  		if (info_dirty(&dqopt->info[dquot->dq_type]))
  			ret2 = dqopt->ops[dquot->dq_type]->write_file_info(dquot->dq_sb, dquot->dq_type);
  		if (ret >= 0)
  			ret = ret2;
  	}
  	clear_bit(DQ_ACTIVE_B, &dquot->dq_flags);

  	mutex_unlock(&dqopt->dqio_mutex);

  out_dqlock:

  	mutex_unlock(&dquot->dq_lock);

  	return ret;
  }

  void dquot_destroy(struct dquot *dquot)

  {
  	kmem_cache_free(dquot_cachep, dquot);
  }

  EXPORT_SYMBOL(dquot_destroy);

  
  static inline void do_destroy_dquot(struct dquot *dquot)
  {
  	dquot->dq_sb->dq_op->destroy_dquot(dquot);
  }

  /* Invalidate all dquots on the list. Note that this function is called after
   * quota is disabled and pointers from inodes removed so there cannot be new

   * quota users. There can still be some users of quotas due to inodes being
   * just deleted or pruned by prune_icache() (those are not attached to any

   * list) or parallel quotactl call. We have to wait for such users.

   */

  static void invalidate_dquots(struct super_block *sb, int type)
  {

  	struct dquot *dquot, *tmp;

  restart:

  	spin_lock(&dq_list_lock);

  	list_for_each_entry_safe(dquot, tmp, &inuse_list, dq_inuse) {

  		if (dquot->dq_sb != sb)
  			continue;
  		if (dquot->dq_type != type)
  			continue;

  		/* Wait for dquot users */
  		if (atomic_read(&dquot->dq_count)) {
  			DEFINE_WAIT(wait);
  
  			atomic_inc(&dquot->dq_count);
  			prepare_to_wait(&dquot->dq_wait_unused, &wait,
  					TASK_UNINTERRUPTIBLE);
  			spin_unlock(&dq_list_lock);
  			/* Once dqput() wakes us up, we know it's time to free
  			 * the dquot.
  			 * IMPORTANT: we rely on the fact that there is always
  			 * at most one process waiting for dquot to free.
  			 * Otherwise dq_count would be > 1 and we would never
  			 * wake up.
  			 */
  			if (atomic_read(&dquot->dq_count) > 1)
  				schedule();
  			finish_wait(&dquot->dq_wait_unused, &wait);
  			dqput(dquot);
  			/* At this moment dquot() need not exist (it could be
  			 * reclaimed by prune_dqcache(). Hence we must
  			 * restart. */
  			goto restart;
  		}
  		/*
  		 * Quota now has no users and it has been written on last
  		 * dqput()
  		 */

  		remove_dquot_hash(dquot);
  		remove_free_dquot(dquot);
  		remove_inuse(dquot);

  		do_destroy_dquot(dquot);

  	}
  	spin_unlock(&dq_list_lock);
  }

  /* Call callback for every active dquot on given filesystem */
  int dquot_scan_active(struct super_block *sb,
  		      int (*fn)(struct dquot *dquot, unsigned long priv),
  		      unsigned long priv)
  {
  	struct dquot *dquot, *old_dquot = NULL;
  	int ret = 0;
  
  	mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
  	spin_lock(&dq_list_lock);
  	list_for_each_entry(dquot, &inuse_list, dq_inuse) {
  		if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags))
  			continue;
  		if (dquot->dq_sb != sb)
  			continue;
  		/* Now we have active dquot so we can just increase use count */
  		atomic_inc(&dquot->dq_count);
  		dqstats.lookups++;
  		spin_unlock(&dq_list_lock);
  		dqput(old_dquot);
  		old_dquot = dquot;
  		ret = fn(dquot, priv);
  		if (ret < 0)
  			goto out;
  		spin_lock(&dq_list_lock);
  		/* We are safe to continue now because our dquot could not
  		 * be moved out of the inuse list while we hold the reference */
  	}
  	spin_unlock(&dq_list_lock);
  out:
  	dqput(old_dquot);
  	mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
  	return ret;
  }

  int vfs_quota_sync(struct super_block *sb, int type)
  {
  	struct list_head *dirty;
  	struct dquot *dquot;
  	struct quota_info *dqopt = sb_dqopt(sb);
  	int cnt;

  	mutex_lock(&dqopt->dqonoff_mutex);

  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  		if (type != -1 && cnt != type)
  			continue;

  		if (!sb_has_quota_active(sb, cnt))

  			continue;
  		spin_lock(&dq_list_lock);
  		dirty = &dqopt->info[cnt].dqi_dirty_list;
  		while (!list_empty(dirty)) {

  			dquot = list_first_entry(dirty, struct dquot, dq_dirty);

  			/* Dirty and inactive can be only bad dquot... */
  			if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
  				clear_dquot_dirty(dquot);
  				continue;
  			}
  			/* Now we have active dquot from which someone is
   			 * holding reference so we can safely just increase
  			 * use count */
  			atomic_inc(&dquot->dq_count);
  			dqstats.lookups++;
  			spin_unlock(&dq_list_lock);
  			sb->dq_op->write_dquot(dquot);
  			dqput(dquot);
  			spin_lock(&dq_list_lock);
  		}
  		spin_unlock(&dq_list_lock);
  	}
  
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++)

  		if ((cnt == type || type == -1) && sb_has_quota_active(sb, cnt)
  		    && info_dirty(&dqopt->info[cnt]))

  			sb->dq_op->write_info(sb, cnt);
  	spin_lock(&dq_list_lock);
  	dqstats.syncs++;
  	spin_unlock(&dq_list_lock);

  	mutex_unlock(&dqopt->dqonoff_mutex);

  
  	return 0;
  }
  
  /* Free unused dquots from cache */
  static void prune_dqcache(int count)
  {
  	struct list_head *head;
  	struct dquot *dquot;
  
  	head = free_dquots.prev;
  	while (head != &free_dquots && count) {
  		dquot = list_entry(head, struct dquot, dq_free);
  		remove_dquot_hash(dquot);
  		remove_free_dquot(dquot);
  		remove_inuse(dquot);

  		do_destroy_dquot(dquot);

  		count--;
  		head = free_dquots.prev;
  	}
  }
  
  /*
   * This is called from kswapd when we think we need some
   * more memory
   */

  static int shrink_dqcache_memory(int nr, gfp_t gfp_mask)

  {
  	if (nr) {
  		spin_lock(&dq_list_lock);
  		prune_dqcache(nr);
  		spin_unlock(&dq_list_lock);
  	}
  	return (dqstats.free_dquots / 100) * sysctl_vfs_cache_pressure;
  }

  static struct shrinker dqcache_shrinker = {
  	.shrink = shrink_dqcache_memory,
  	.seeks = DEFAULT_SEEKS,
  };

  /*
   * Put reference to dquot
   * NOTE: If you change this function please check whether dqput_blocks() works right...

   */

  void dqput(struct dquot *dquot)

  {

  	int ret;

  	if (!dquot)
  		return;
  #ifdef __DQUOT_PARANOIA
  	if (!atomic_read(&dquot->dq_count)) {
  		printk("VFS: dqput: trying to free free dquot
  ");
  		printk("VFS: device %s, dquot of %s %d
  ",
  			dquot->dq_sb->s_id,
  			quotatypes[dquot->dq_type],
  			dquot->dq_id);
  		BUG();
  	}
  #endif
  	
  	spin_lock(&dq_list_lock);
  	dqstats.drops++;
  	spin_unlock(&dq_list_lock);
  we_slept:
  	spin_lock(&dq_list_lock);
  	if (atomic_read(&dquot->dq_count) > 1) {
  		/* We have more than one user... nothing to do */
  		atomic_dec(&dquot->dq_count);

  		/* Releasing dquot during quotaoff phase? */

  		if (!sb_has_quota_active(dquot->dq_sb, dquot->dq_type) &&

  		    atomic_read(&dquot->dq_count) == 1)
  			wake_up(&dquot->dq_wait_unused);

  		spin_unlock(&dq_list_lock);
  		return;
  	}
  	/* Need to release dquot? */
  	if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && dquot_dirty(dquot)) {
  		spin_unlock(&dq_list_lock);
  		/* Commit dquot before releasing */

  		ret = dquot->dq_sb->dq_op->write_dquot(dquot);
  		if (ret < 0) {
  			printk(KERN_ERR "VFS: cannot write quota structure on "
  				"device %s (error %d). Quota may get out of "
  				"sync!
  ", dquot->dq_sb->s_id, ret);
  			/*
  			 * We clear dirty bit anyway, so that we avoid
  			 * infinite loop here
  			 */
  			spin_lock(&dq_list_lock);
  			clear_dquot_dirty(dquot);
  			spin_unlock(&dq_list_lock);
  		}

  		goto we_slept;
  	}
  	/* Clear flag in case dquot was inactive (something bad happened) */
  	clear_dquot_dirty(dquot);
  	if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
  		spin_unlock(&dq_list_lock);
  		dquot->dq_sb->dq_op->release_dquot(dquot);
  		goto we_slept;
  	}
  	atomic_dec(&dquot->dq_count);
  #ifdef __DQUOT_PARANOIA
  	/* sanity check */

  	BUG_ON(!list_empty(&dquot->dq_free));

  #endif
  	put_dquot_last(dquot);
  	spin_unlock(&dq_list_lock);
  }

  struct dquot *dquot_alloc(struct super_block *sb, int type)

  {
  	return kmem_cache_zalloc(dquot_cachep, GFP_NOFS);
  }

  EXPORT_SYMBOL(dquot_alloc);

  static struct dquot *get_empty_dquot(struct super_block *sb, int type)
  {
  	struct dquot *dquot;

  	dquot = sb->dq_op->alloc_dquot(sb, type);

  	if(!dquot)
  		return NODQUOT;

  	mutex_init(&dquot->dq_lock);

  	INIT_LIST_HEAD(&dquot->dq_free);
  	INIT_LIST_HEAD(&dquot->dq_inuse);
  	INIT_HLIST_NODE(&dquot->dq_hash);
  	INIT_LIST_HEAD(&dquot->dq_dirty);

  	init_waitqueue_head(&dquot->dq_wait_unused);

  	dquot->dq_sb = sb;
  	dquot->dq_type = type;
  	atomic_set(&dquot->dq_count, 1);
  
  	return dquot;
  }
  
  /*
   * Get reference to dquot

   *
   * Locking is slightly tricky here. We are guarded from parallel quotaoff()
   * destroying our dquot by:
   *   a) checking for quota flags under dq_list_lock and
   *   b) getting a reference to dquot before we release dq_list_lock

   */

  struct dquot *dqget(struct super_block *sb, unsigned int id, int type)

  {
  	unsigned int hashent = hashfn(sb, id, type);

  	struct dquot *dquot = NODQUOT, *empty = NODQUOT;

          if (!sb_has_quota_active(sb, type))

  		return NODQUOT;
  we_slept:
  	spin_lock(&dq_list_lock);

  	spin_lock(&dq_state_lock);
  	if (!sb_has_quota_active(sb, type)) {
  		spin_unlock(&dq_state_lock);
  		spin_unlock(&dq_list_lock);
  		goto out;
  	}
  	spin_unlock(&dq_state_lock);

  	if ((dquot = find_dquot(hashent, sb, id, type)) == NODQUOT) {
  		if (empty == NODQUOT) {
  			spin_unlock(&dq_list_lock);
  			if ((empty = get_empty_dquot(sb, type)) == NODQUOT)
  				schedule();	/* Try to wait for a moment... */
  			goto we_slept;
  		}
  		dquot = empty;

  		empty = NODQUOT;

  		dquot->dq_id = id;
  		/* all dquots go on the inuse_list */
  		put_inuse(dquot);
  		/* hash it first so it can be found */
  		insert_dquot_hash(dquot);
  		dqstats.lookups++;
  		spin_unlock(&dq_list_lock);
  	} else {
  		if (!atomic_read(&dquot->dq_count))
  			remove_free_dquot(dquot);
  		atomic_inc(&dquot->dq_count);
  		dqstats.cache_hits++;
  		dqstats.lookups++;
  		spin_unlock(&dq_list_lock);

  	}
  	/* Wait for dq_lock - after this we know that either dquot_release() is already
  	 * finished or it will be canceled due to dq_count > 1 test */
  	wait_on_dquot(dquot);
  	/* Read the dquot and instantiate it (everything done only if needed) */
  	if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && sb->dq_op->acquire_dquot(dquot) < 0) {
  		dqput(dquot);

  		dquot = NODQUOT;
  		goto out;

  	}
  #ifdef __DQUOT_PARANOIA

  	BUG_ON(!dquot->dq_sb);	/* Has somebody invalidated entry under us? */

  #endif

  out:
  	if (empty)
  		do_destroy_dquot(empty);

  
  	return dquot;
  }
  
  static int dqinit_needed(struct inode *inode, int type)
  {
  	int cnt;
  
  	if (IS_NOQUOTA(inode))
  		return 0;
  	if (type != -1)
  		return inode->i_dquot[type] == NODQUOT;
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
  		if (inode->i_dquot[cnt] == NODQUOT)
  			return 1;
  	return 0;
  }

  /* This routine is guarded by dqonoff_mutex mutex */

  static void add_dquot_ref(struct super_block *sb, int type)
  {

  	struct inode *inode, *old_inode = NULL;

  	spin_lock(&inode_lock);
  	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
  		if (!atomic_read(&inode->i_writecount))
  			continue;
  		if (!dqinit_needed(inode, type))
  			continue;
  		if (inode->i_state & (I_FREEING|I_WILL_FREE))
  			continue;
  
  		__iget(inode);
  		spin_unlock(&inode_lock);

  		iput(old_inode);

  		sb->dq_op->initialize(inode, type);

  		/* We hold a reference to 'inode' so it couldn't have been
  		 * removed from s_inodes list while we dropped the inode_lock.
  		 * We cannot iput the inode now as we can be holding the last
  		 * reference and we cannot iput it under inode_lock. So we
  		 * keep the reference and iput it later. */
  		old_inode = inode;
  		spin_lock(&inode_lock);

  	}

  	spin_unlock(&inode_lock);

  	iput(old_inode);

  }
  
  /* Return 0 if dqput() won't block (note that 1 doesn't necessarily mean blocking) */
  static inline int dqput_blocks(struct dquot *dquot)
  {
  	if (atomic_read(&dquot->dq_count) <= 1)
  		return 1;
  	return 0;
  }
  
  /* Remove references to dquots from inode - add dquot to list for freeing if needed */
  /* We can't race with anybody because we hold dqptr_sem for writing... */

  static int remove_inode_dquot_ref(struct inode *inode, int type,
  				  struct list_head *tofree_head)

  {
  	struct dquot *dquot = inode->i_dquot[type];
  
  	inode->i_dquot[type] = NODQUOT;
  	if (dquot != NODQUOT) {
  		if (dqput_blocks(dquot)) {
  #ifdef __DQUOT_PARANOIA
  			if (atomic_read(&dquot->dq_count) != 1)
  				printk(KERN_WARNING "VFS: Adding dquot with dq_count %d to dispose list.
  ", atomic_read(&dquot->dq_count));
  #endif
  			spin_lock(&dq_list_lock);
  			list_add(&dquot->dq_free, tofree_head);	/* As dquot must have currently users it can't be on the free list... */
  			spin_unlock(&dq_list_lock);
  			return 1;
  		}
  		else
  			dqput(dquot);   /* We have guaranteed we won't block */
  	}
  	return 0;
  }
  
  /* Free list of dquots - called from inode.c */
  /* dquots are removed from inodes, no new references can be got so we are the only ones holding reference */
  static void put_dquot_list(struct list_head *tofree_head)
  {
  	struct list_head *act_head;
  	struct dquot *dquot;
  
  	act_head = tofree_head->next;
  	/* So now we have dquots on the list... Just free them */
  	while (act_head != tofree_head) {
  		dquot = list_entry(act_head, struct dquot, dq_free);
  		act_head = act_head->next;
  		list_del_init(&dquot->dq_free);	/* Remove dquot from the list so we won't have problems... */
  		dqput(dquot);
  	}
  }

  static void remove_dquot_ref(struct super_block *sb, int type,
  		struct list_head *tofree_head)
  {
  	struct inode *inode;
  
  	spin_lock(&inode_lock);
  	list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
  		if (!IS_NOQUOTA(inode))
  			remove_inode_dquot_ref(inode, type, tofree_head);
  	}
  	spin_unlock(&inode_lock);
  }

  /* Gather all references from inodes and drop them */
  static void drop_dquot_ref(struct super_block *sb, int type)
  {
  	LIST_HEAD(tofree_head);

  	if (sb->dq_op) {
  		down_write(&sb_dqopt(sb)->dqptr_sem);
  		remove_dquot_ref(sb, type, &tofree_head);
  		up_write(&sb_dqopt(sb)->dqptr_sem);
  		put_dquot_list(&tofree_head);
  	}

  }

  static inline void dquot_incr_inodes(struct dquot *dquot, qsize_t number)

  {
  	dquot->dq_dqb.dqb_curinodes += number;
  }
  
  static inline void dquot_incr_space(struct dquot *dquot, qsize_t number)
  {
  	dquot->dq_dqb.dqb_curspace += number;
  }

  static inline void dquot_decr_inodes(struct dquot *dquot, qsize_t number)

  {

  	if (sb_dqopt(dquot->dq_sb)->flags & DQUOT_NEGATIVE_USAGE ||
  	    dquot->dq_dqb.dqb_curinodes >= number)

  		dquot->dq_dqb.dqb_curinodes -= number;
  	else
  		dquot->dq_dqb.dqb_curinodes = 0;
  	if (dquot->dq_dqb.dqb_curinodes <= dquot->dq_dqb.dqb_isoftlimit)
  		dquot->dq_dqb.dqb_itime = (time_t) 0;
  	clear_bit(DQ_INODES_B, &dquot->dq_flags);
  }
  
  static inline void dquot_decr_space(struct dquot *dquot, qsize_t number)
  {

  	if (sb_dqopt(dquot->dq_sb)->flags & DQUOT_NEGATIVE_USAGE ||
  	    dquot->dq_dqb.dqb_curspace >= number)

  		dquot->dq_dqb.dqb_curspace -= number;
  	else
  		dquot->dq_dqb.dqb_curspace = 0;

  	if (dquot->dq_dqb.dqb_curspace <= dquot->dq_dqb.dqb_bsoftlimit)

  		dquot->dq_dqb.dqb_btime = (time_t) 0;
  	clear_bit(DQ_BLKS_B, &dquot->dq_flags);
  }

  static int warning_issued(struct dquot *dquot, const int warntype)
  {
  	int flag = (warntype == QUOTA_NL_BHARDWARN ||
  		warntype == QUOTA_NL_BSOFTLONGWARN) ? DQ_BLKS_B :
  		((warntype == QUOTA_NL_IHARDWARN ||
  		warntype == QUOTA_NL_ISOFTLONGWARN) ? DQ_INODES_B : 0);
  
  	if (!flag)
  		return 0;
  	return test_and_set_bit(flag, &dquot->dq_flags);
  }

  #ifdef CONFIG_PRINT_QUOTA_WARNING

  static int flag_print_warnings = 1;
  
  static inline int need_print_warning(struct dquot *dquot)
  {
  	if (!flag_print_warnings)
  		return 0;
  
  	switch (dquot->dq_type) {
  		case USRQUOTA:

  			return current_fsuid() == dquot->dq_id;

  		case GRPQUOTA:
  			return in_group_p(dquot->dq_id);
  	}
  	return 0;
  }

  /* Print warning to user which exceeded quota */

  static void print_warning(struct dquot *dquot, const int warntype)

  {
  	char *msg = NULL;

  	struct tty_struct *tty;

  	if (warntype == QUOTA_NL_IHARDBELOW ||
  	    warntype == QUOTA_NL_ISOFTBELOW ||
  	    warntype == QUOTA_NL_BHARDBELOW ||
  	    warntype == QUOTA_NL_BSOFTBELOW || !need_print_warning(dquot))

  		return;

  	tty = get_current_tty();
  	if (!tty)

  		return;

  	tty_write_message(tty, dquot->dq_sb->s_id);

  	if (warntype == QUOTA_NL_ISOFTWARN || warntype == QUOTA_NL_BSOFTWARN)

  		tty_write_message(tty, ": warning, ");

  	else

  		tty_write_message(tty, ": write failed, ");
  	tty_write_message(tty, quotatypes[dquot->dq_type]);

  	switch (warntype) {

  		case QUOTA_NL_IHARDWARN:

  			msg = " file limit reached.\r
  ";
  			break;

  		case QUOTA_NL_ISOFTLONGWARN:

  			msg = " file quota exceeded too long.\r
  ";
  			break;

  		case QUOTA_NL_ISOFTWARN:

  			msg = " file quota exceeded.\r
  ";
  			break;

  		case QUOTA_NL_BHARDWARN:

  			msg = " block limit reached.\r
  ";
  			break;

  		case QUOTA_NL_BSOFTLONGWARN:

  			msg = " block quota exceeded too long.\r
  ";
  			break;

  		case QUOTA_NL_BSOFTWARN:

  			msg = " block quota exceeded.\r
  ";
  			break;
  	}

  	tty_write_message(tty, msg);

  	tty_kref_put(tty);

  }

  #endif
  
  #ifdef CONFIG_QUOTA_NETLINK_INTERFACE

  /* Netlink family structure for quota */
  static struct genl_family quota_genl_family = {
  	.id = GENL_ID_GENERATE,
  	.hdrsize = 0,
  	.name = "VFS_DQUOT",
  	.version = 1,
  	.maxattr = QUOTA_NL_A_MAX,
  };
  
  /* Send warning to userspace about user which exceeded quota */
  static void send_warning(const struct dquot *dquot, const char warntype)
  {
  	static atomic_t seq;
  	struct sk_buff *skb;
  	void *msg_head;
  	int ret;

  	int msg_size = 4 * nla_total_size(sizeof(u32)) +
  		       2 * nla_total_size(sizeof(u64));

  
  	/* We have to allocate using GFP_NOFS as we are called from a
  	 * filesystem performing write and thus further recursion into
  	 * the fs to free some data could cause deadlocks. */

  	skb = genlmsg_new(msg_size, GFP_NOFS);

  	if (!skb) {
  		printk(KERN_ERR
  		  "VFS: Not enough memory to send quota warning.
  ");
  		return;
  	}
  	msg_head = genlmsg_put(skb, 0, atomic_add_return(1, &seq),
  			&quota_genl_family, 0, QUOTA_NL_C_WARNING);
  	if (!msg_head) {
  		printk(KERN_ERR
  		  "VFS: Cannot store netlink header in quota warning.
  ");
  		goto err_out;
  	}
  	ret = nla_put_u32(skb, QUOTA_NL_A_QTYPE, dquot->dq_type);
  	if (ret)
  		goto attr_err_out;
  	ret = nla_put_u64(skb, QUOTA_NL_A_EXCESS_ID, dquot->dq_id);
  	if (ret)
  		goto attr_err_out;
  	ret = nla_put_u32(skb, QUOTA_NL_A_WARNING, warntype);
  	if (ret)
  		goto attr_err_out;
  	ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MAJOR,
  		MAJOR(dquot->dq_sb->s_dev));
  	if (ret)
  		goto attr_err_out;
  	ret = nla_put_u32(skb, QUOTA_NL_A_DEV_MINOR,
  		MINOR(dquot->dq_sb->s_dev));
  	if (ret)
  		goto attr_err_out;

  	ret = nla_put_u64(skb, QUOTA_NL_A_CAUSED_ID, current_uid());

  	if (ret)
  		goto attr_err_out;
  	genlmsg_end(skb, msg_head);
  
  	ret = genlmsg_multicast(skb, 0, quota_genl_family.id, GFP_NOFS);
  	if (ret < 0 && ret != -ESRCH)
  		printk(KERN_ERR
  			"VFS: Failed to send notification message: %d
  ", ret);
  	return;
  attr_err_out:

  	printk(KERN_ERR "VFS: Not enough space to compose quota message!
  ");

  err_out:
  	kfree_skb(skb);
  }
  #endif

  static inline void flush_warnings(struct dquot * const *dquots, char *warntype)

  {
  	int i;
  
  	for (i = 0; i < MAXQUOTAS; i++)

  		if (dquots[i] != NODQUOT && warntype[i] != QUOTA_NL_NOWARN &&
  		    !warning_issued(dquots[i], warntype[i])) {

  #ifdef CONFIG_PRINT_QUOTA_WARNING

  			print_warning(dquots[i], warntype[i]);

  #endif
  #ifdef CONFIG_QUOTA_NETLINK_INTERFACE
  			send_warning(dquots[i], warntype[i]);
  #endif
  		}

  }
  
  static inline char ignore_hardlimit(struct dquot *dquot)
  {
  	struct mem_dqinfo *info = &sb_dqopt(dquot->dq_sb)->info[dquot->dq_type];
  
  	return capable(CAP_SYS_RESOURCE) &&
  	    (info->dqi_format->qf_fmt_id != QFMT_VFS_OLD || !(info->dqi_flags & V1_DQF_RSQUASH));
  }
  
  /* needs dq_data_lock */

  static int check_idq(struct dquot *dquot, qsize_t inodes, char *warntype)

  {

  	*warntype = QUOTA_NL_NOWARN;

  	if (!sb_has_quota_limits_enabled(dquot->dq_sb, dquot->dq_type) ||
  	    test_bit(DQ_FAKE_B, &dquot->dq_flags))

  		return QUOTA_OK;
  
  	if (dquot->dq_dqb.dqb_ihardlimit &&
  	   (dquot->dq_dqb.dqb_curinodes + inodes) > dquot->dq_dqb.dqb_ihardlimit &&
              !ignore_hardlimit(dquot)) {

  		*warntype = QUOTA_NL_IHARDWARN;

  		return NO_QUOTA;
  	}
  
  	if (dquot->dq_dqb.dqb_isoftlimit &&
  	   (dquot->dq_dqb.dqb_curinodes + inodes) > dquot->dq_dqb.dqb_isoftlimit &&
  	    dquot->dq_dqb.dqb_itime && get_seconds() >= dquot->dq_dqb.dqb_itime &&
              !ignore_hardlimit(dquot)) {

  		*warntype = QUOTA_NL_ISOFTLONGWARN;

  		return NO_QUOTA;
  	}
  
  	if (dquot->dq_dqb.dqb_isoftlimit &&
  	   (dquot->dq_dqb.dqb_curinodes + inodes) > dquot->dq_dqb.dqb_isoftlimit &&
  	    dquot->dq_dqb.dqb_itime == 0) {

  		*warntype = QUOTA_NL_ISOFTWARN;

  		dquot->dq_dqb.dqb_itime = get_seconds() + sb_dqopt(dquot->dq_sb)->info[dquot->dq_type].dqi_igrace;
  	}
  
  	return QUOTA_OK;
  }
  
  /* needs dq_data_lock */
  static int check_bdq(struct dquot *dquot, qsize_t space, int prealloc, char *warntype)
  {

  	*warntype = QUOTA_NL_NOWARN;

  	if (!sb_has_quota_limits_enabled(dquot->dq_sb, dquot->dq_type) ||
  	    test_bit(DQ_FAKE_B, &dquot->dq_flags))

  		return QUOTA_OK;
  
  	if (dquot->dq_dqb.dqb_bhardlimit &&

  	    dquot->dq_dqb.dqb_curspace + space > dquot->dq_dqb.dqb_bhardlimit &&

              !ignore_hardlimit(dquot)) {
  		if (!prealloc)

  			*warntype = QUOTA_NL_BHARDWARN;

  		return NO_QUOTA;
  	}
  
  	if (dquot->dq_dqb.dqb_bsoftlimit &&

  	    dquot->dq_dqb.dqb_curspace + space > dquot->dq_dqb.dqb_bsoftlimit &&

  	    dquot->dq_dqb.dqb_btime && get_seconds() >= dquot->dq_dqb.dqb_btime &&
              !ignore_hardlimit(dquot)) {
  		if (!prealloc)

  			*warntype = QUOTA_NL_BSOFTLONGWARN;

  		return NO_QUOTA;
  	}
  
  	if (dquot->dq_dqb.dqb_bsoftlimit &&

  	    dquot->dq_dqb.dqb_curspace + space > dquot->dq_dqb.dqb_bsoftlimit &&

  	    dquot->dq_dqb.dqb_btime == 0) {
  		if (!prealloc) {

  			*warntype = QUOTA_NL_BSOFTWARN;

  			dquot->dq_dqb.dqb_btime = get_seconds() + sb_dqopt(dquot->dq_sb)->info[dquot->dq_type].dqi_bgrace;
  		}
  		else
  			/*
  			 * We don't allow preallocation to exceed softlimit so exceeding will
  			 * be always printed
  			 */
  			return NO_QUOTA;
  	}
  
  	return QUOTA_OK;
  }

  static int info_idq_free(struct dquot *dquot, qsize_t inodes)

  {
  	if (test_bit(DQ_FAKE_B, &dquot->dq_flags) ||

  	    dquot->dq_dqb.dqb_curinodes <= dquot->dq_dqb.dqb_isoftlimit ||
  	    !sb_has_quota_limits_enabled(dquot->dq_sb, dquot->dq_type))

  		return QUOTA_NL_NOWARN;
  
  	if (dquot->dq_dqb.dqb_curinodes - inodes <= dquot->dq_dqb.dqb_isoftlimit)
  		return QUOTA_NL_ISOFTBELOW;
  	if (dquot->dq_dqb.dqb_curinodes >= dquot->dq_dqb.dqb_ihardlimit &&
  	    dquot->dq_dqb.dqb_curinodes - inodes < dquot->dq_dqb.dqb_ihardlimit)
  		return QUOTA_NL_IHARDBELOW;
  	return QUOTA_NL_NOWARN;
  }
  
  static int info_bdq_free(struct dquot *dquot, qsize_t space)
  {
  	if (test_bit(DQ_FAKE_B, &dquot->dq_flags) ||

  	    dquot->dq_dqb.dqb_curspace <= dquot->dq_dqb.dqb_bsoftlimit)

  		return QUOTA_NL_NOWARN;

  	if (dquot->dq_dqb.dqb_curspace - space <= dquot->dq_dqb.dqb_bsoftlimit)

  		return QUOTA_NL_BSOFTBELOW;

  	if (dquot->dq_dqb.dqb_curspace >= dquot->dq_dqb.dqb_bhardlimit &&
  	    dquot->dq_dqb.dqb_curspace - space < dquot->dq_dqb.dqb_bhardlimit)

  		return QUOTA_NL_BHARDBELOW;
  	return QUOTA_NL_NOWARN;
  }

  /*
   *	Initialize quota pointers in inode

   *	We do things in a bit complicated way but by that we avoid calling
   *	dqget() and thus filesystem callbacks under dqptr_sem.

   */
  int dquot_initialize(struct inode *inode, int type)
  {
  	unsigned int id = 0;
  	int cnt, ret = 0;

  	struct dquot *got[MAXQUOTAS] = { NODQUOT, NODQUOT };
  	struct super_block *sb = inode->i_sb;

  	/* First test before acquiring mutex - solves deadlocks when we
           * re-enter the quota code and are already holding the mutex */

  	if (IS_NOQUOTA(inode))
  		return 0;

  
  	/* First get references to structures we might need. */
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  		if (type != -1 && cnt != type)
  			continue;
  		switch (cnt) {
  		case USRQUOTA:
  			id = inode->i_uid;
  			break;
  		case GRPQUOTA:
  			id = inode->i_gid;
  			break;
  		}
  		got[cnt] = dqget(sb, id, cnt);
  	}
  
  	down_write(&sb_dqopt(sb)->dqptr_sem);

  	/* Having dqptr_sem we know NOQUOTA flags can't be altered... */
  	if (IS_NOQUOTA(inode))
  		goto out_err;
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  		if (type != -1 && cnt != type)
  			continue;

  		/* Avoid races with quotaoff() */
  		if (!sb_has_quota_active(sb, cnt))
  			continue;

  		if (inode->i_dquot[cnt] == NODQUOT) {

  			inode->i_dquot[cnt] = got[cnt];
  			got[cnt] = NODQUOT;

  		}
  	}
  out_err:

  	up_write(&sb_dqopt(sb)->dqptr_sem);
  	/* Drop unused references */
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
  		dqput(got[cnt]);

  	return ret;
  }
  
  /*
   * 	Release all quotas referenced by inode

   */

  int dquot_drop(struct inode *inode)

  {
  	int cnt;

  	struct dquot *put[MAXQUOTAS];

  	down_write(&sb_dqopt(inode->i_sb)->dqptr_sem);

  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {

  		put[cnt] = inode->i_dquot[cnt];
  		inode->i_dquot[cnt] = NODQUOT;

  	}
  	up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);

  
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
  		dqput(put[cnt]);

  	return 0;
  }

  /* Wrapper to remove references to quota structures from inode */
  void vfs_dq_drop(struct inode *inode)
  {
  	/* Here we can get arbitrary inode from clear_inode() so we have
  	 * to be careful. OTOH we don't need locking as quota operations
  	 * are allowed to change only at mount time */
  	if (!IS_NOQUOTA(inode) && inode->i_sb && inode->i_sb->dq_op
  	    && inode->i_sb->dq_op->drop) {
  		int cnt;
  		/* Test before calling to rule out calls from proc and such
                   * where we are not allowed to block. Note that this is
  		 * actually reliable test even without the lock - the caller
  		 * must assure that nobody can come after the DQUOT_DROP and
  		 * add quota pointers back anyway */
  		for (cnt = 0; cnt < MAXQUOTAS; cnt++)
  			if (inode->i_dquot[cnt] != NODQUOT)
  				break;
  		if (cnt < MAXQUOTAS)
  			inode->i_sb->dq_op->drop(inode);
  	}
  }

  /*
   * Following four functions update i_blocks+i_bytes fields and
   * quota information (together with appropriate checks)
   * NOTE: We absolutely rely on the fact that caller dirties
   * the inode (usually macros in quotaops.h care about this) and
   * holds a handle for the current transaction so that dquot write and
   * inode write go into the same transaction.
   */
  
  /*
   * This operation can block, but only after everything is updated
   */
  int dquot_alloc_space(struct inode *inode, qsize_t number, int warn)
  {
  	int cnt, ret = NO_QUOTA;
  	char warntype[MAXQUOTAS];

  	/* First test before acquiring mutex - solves deadlocks when we
           * re-enter the quota code and are already holding the mutex */

  	if (IS_NOQUOTA(inode)) {
  out_add:
  		inode_add_bytes(inode, number);
  		return QUOTA_OK;
  	}
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++)

  		warntype[cnt] = QUOTA_NL_NOWARN;

  
  	down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
  	if (IS_NOQUOTA(inode)) {	/* Now we can do reliable test... */
  		up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
  		goto out_add;
  	}
  	spin_lock(&dq_data_lock);
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  		if (inode->i_dquot[cnt] == NODQUOT)
  			continue;
  		if (check_bdq(inode->i_dquot[cnt], number, warn, warntype+cnt) == NO_QUOTA)
  			goto warn_put_all;
  	}
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  		if (inode->i_dquot[cnt] == NODQUOT)
  			continue;
  		dquot_incr_space(inode->i_dquot[cnt], number);
  	}
  	inode_add_bytes(inode, number);
  	ret = QUOTA_OK;
  warn_put_all:
  	spin_unlock(&dq_data_lock);
  	if (ret == QUOTA_OK)
  		/* Dirtify all the dquots - this can block when journalling */
  		for (cnt = 0; cnt < MAXQUOTAS; cnt++)
  			if (inode->i_dquot[cnt])
  				mark_dquot_dirty(inode->i_dquot[cnt]);
  	flush_warnings(inode->i_dquot, warntype);
  	up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
  	return ret;
  }
  
  /*
   * This operation can block, but only after everything is updated
   */

  int dquot_alloc_inode(const struct inode *inode, qsize_t number)

  {
  	int cnt, ret = NO_QUOTA;
  	char warntype[MAXQUOTAS];

  	/* First test before acquiring mutex - solves deadlocks when we
           * re-enter the quota code and are already holding the mutex */

  	if (IS_NOQUOTA(inode))
  		return QUOTA_OK;
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++)

  		warntype[cnt] = QUOTA_NL_NOWARN;

  	down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
  	if (IS_NOQUOTA(inode)) {
  		up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
  		return QUOTA_OK;
  	}
  	spin_lock(&dq_data_lock);
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  		if (inode->i_dquot[cnt] == NODQUOT)
  			continue;
  		if (check_idq(inode->i_dquot[cnt], number, warntype+cnt) == NO_QUOTA)
  			goto warn_put_all;
  	}
  
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  		if (inode->i_dquot[cnt] == NODQUOT)
  			continue;
  		dquot_incr_inodes(inode->i_dquot[cnt], number);
  	}
  	ret = QUOTA_OK;
  warn_put_all:
  	spin_unlock(&dq_data_lock);
  	if (ret == QUOTA_OK)
  		/* Dirtify all the dquots - this can block when journalling */
  		for (cnt = 0; cnt < MAXQUOTAS; cnt++)
  			if (inode->i_dquot[cnt])
  				mark_dquot_dirty(inode->i_dquot[cnt]);

  	flush_warnings(inode->i_dquot, warntype);

  	up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
  	return ret;
  }
  
  /*
   * This operation can block, but only after everything is updated
   */
  int dquot_free_space(struct inode *inode, qsize_t number)
  {
  	unsigned int cnt;

  	char warntype[MAXQUOTAS];

  	/* First test before acquiring mutex - solves deadlocks when we
           * re-enter the quota code and are already holding the mutex */

  	if (IS_NOQUOTA(inode)) {
  out_sub:
  		inode_sub_bytes(inode, number);
  		return QUOTA_OK;
  	}

  	down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
  	/* Now recheck reliably when holding dqptr_sem */
  	if (IS_NOQUOTA(inode)) {
  		up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
  		goto out_sub;
  	}
  	spin_lock(&dq_data_lock);
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  		if (inode->i_dquot[cnt] == NODQUOT)
  			continue;

  		warntype[cnt] = info_bdq_free(inode->i_dquot[cnt], number);

  		dquot_decr_space(inode->i_dquot[cnt], number);
  	}
  	inode_sub_bytes(inode, number);
  	spin_unlock(&dq_data_lock);
  	/* Dirtify all the dquots - this can block when journalling */
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
  		if (inode->i_dquot[cnt])
  			mark_dquot_dirty(inode->i_dquot[cnt]);

  	flush_warnings(inode->i_dquot, warntype);

  	up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
  	return QUOTA_OK;
  }
  
  /*
   * This operation can block, but only after everything is updated
   */

  int dquot_free_inode(const struct inode *inode, qsize_t number)

  {
  	unsigned int cnt;

  	char warntype[MAXQUOTAS];

  	/* First test before acquiring mutex - solves deadlocks when we
           * re-enter the quota code and are already holding the mutex */

  	if (IS_NOQUOTA(inode))
  		return QUOTA_OK;

  	down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
  	/* Now recheck reliably when holding dqptr_sem */
  	if (IS_NOQUOTA(inode)) {
  		up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
  		return QUOTA_OK;
  	}
  	spin_lock(&dq_data_lock);
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  		if (inode->i_dquot[cnt] == NODQUOT)
  			continue;

  		warntype[cnt] = info_idq_free(inode->i_dquot[cnt], number);

  		dquot_decr_inodes(inode->i_dquot[cnt], number);
  	}
  	spin_unlock(&dq_data_lock);
  	/* Dirtify all the dquots - this can block when journalling */
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
  		if (inode->i_dquot[cnt])
  			mark_dquot_dirty(inode->i_dquot[cnt]);

  	flush_warnings(inode->i_dquot, warntype);

  	up_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
  	return QUOTA_OK;
  }
  
  /*
   * Transfer the number of inode and blocks from one diskquota to an other.
   *
   * This operation can block, but only after everything is updated
   * A transaction must be started when entering this function.
   */
  int dquot_transfer(struct inode *inode, struct iattr *iattr)
  {
  	qsize_t space;
  	struct dquot *transfer_from[MAXQUOTAS];
  	struct dquot *transfer_to[MAXQUOTAS];

  	int cnt, ret = QUOTA_OK;
  	int chuid = iattr->ia_valid & ATTR_UID && inode->i_uid != iattr->ia_uid,
  	    chgid = iattr->ia_valid & ATTR_GID && inode->i_gid != iattr->ia_gid;

  	char warntype_to[MAXQUOTAS];
  	char warntype_from_inodes[MAXQUOTAS], warntype_from_space[MAXQUOTAS];

  	/* First test before acquiring mutex - solves deadlocks when we
           * re-enter the quota code and are already holding the mutex */

  	if (IS_NOQUOTA(inode))
  		return QUOTA_OK;

  	/* Initialize the arrays */

  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {

  		transfer_from[cnt] = NODQUOT;
  		transfer_to[cnt] = NODQUOT;

  		warntype_to[cnt] = QUOTA_NL_NOWARN;

  		switch (cnt) {
  			case USRQUOTA:
  				if (!chuid)
  					continue;
  				transfer_to[cnt] = dqget(inode->i_sb, iattr->ia_uid, cnt);
  				break;
  			case GRPQUOTA:
  				if (!chgid)
  					continue;
  				transfer_to[cnt] = dqget(inode->i_sb, iattr->ia_gid, cnt);
  				break;
  		}
  	}

  
  	down_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
  	/* Now recheck reliably when holding dqptr_sem */
  	if (IS_NOQUOTA(inode)) {	/* File without quota accounting? */
  		up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
  		goto put_all;
  	}

  	spin_lock(&dq_data_lock);
  	space = inode_get_bytes(inode);
  	/* Build the transfer_from list and check the limits */
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  		if (transfer_to[cnt] == NODQUOT)
  			continue;
  		transfer_from[cnt] = inode->i_dquot[cnt];

  		if (check_idq(transfer_to[cnt], 1, warntype_to + cnt) ==
  		    NO_QUOTA || check_bdq(transfer_to[cnt], space, 0,
  		    warntype_to + cnt) == NO_QUOTA)

  			goto over_quota;

  	}
  
  	/*
  	 * Finally perform the needed transfer from transfer_from to transfer_to
  	 */
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  		/*
  		 * Skip changes for same uid or gid or for turned off quota-type.
  		 */
  		if (transfer_to[cnt] == NODQUOT)
  			continue;
  
  		/* Due to IO error we might not have transfer_from[] structure */
  		if (transfer_from[cnt]) {

  			warntype_from_inodes[cnt] =
  				info_idq_free(transfer_from[cnt], 1);
  			warntype_from_space[cnt] =
  				info_bdq_free(transfer_from[cnt], space);

  			dquot_decr_inodes(transfer_from[cnt], 1);
  			dquot_decr_space(transfer_from[cnt], space);
  		}
  
  		dquot_incr_inodes(transfer_to[cnt], 1);
  		dquot_incr_space(transfer_to[cnt], space);
  
  		inode->i_dquot[cnt] = transfer_to[cnt];
  	}

  	spin_unlock(&dq_data_lock);

  	up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);

  	/* Dirtify all the dquots - this can block when journalling */
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  		if (transfer_from[cnt])
  			mark_dquot_dirty(transfer_from[cnt]);

  		if (transfer_to[cnt]) {

  			mark_dquot_dirty(transfer_to[cnt]);

  			/* The reference we got is transferred to the inode */
  			transfer_to[cnt] = NODQUOT;
  		}

  	}

  warn_put_all:

  	flush_warnings(transfer_to, warntype_to);
  	flush_warnings(transfer_from, warntype_from_inodes);
  	flush_warnings(transfer_from, warntype_from_space);

  put_all:

  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {

  		dqput(transfer_from[cnt]);
  		dqput(transfer_to[cnt]);

  	}

  	return ret;

  over_quota:
  	spin_unlock(&dq_data_lock);
  	up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
  	/* Clear dquot pointers we don't want to dqput() */
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
  		transfer_from[cnt] = NODQUOT;
  	ret = NO_QUOTA;
  	goto warn_put_all;

  }

  /* Wrapper for transferring ownership of an inode */
  int vfs_dq_transfer(struct inode *inode, struct iattr *iattr)
  {

  	if (sb_any_quota_active(inode->i_sb) && !IS_NOQUOTA(inode)) {

  		vfs_dq_init(inode);
  		if (inode->i_sb->dq_op->transfer(inode, iattr) == NO_QUOTA)
  			return 1;
  	}
  	return 0;
  }

  /*
   * Write info of quota file to disk
   */
  int dquot_commit_info(struct super_block *sb, int type)
  {
  	int ret;
  	struct quota_info *dqopt = sb_dqopt(sb);

  	mutex_lock(&dqopt->dqio_mutex);

  	ret = dqopt->ops[type]->write_file_info(sb, type);

  	mutex_unlock(&dqopt->dqio_mutex);

  	return ret;
  }
  
  /*
   * Definitions of diskquota operations.
   */
  struct dquot_operations dquot_operations = {
  	.initialize	= dquot_initialize,
  	.drop		= dquot_drop,
  	.alloc_space	= dquot_alloc_space,
  	.alloc_inode	= dquot_alloc_inode,
  	.free_space	= dquot_free_space,
  	.free_inode	= dquot_free_inode,
  	.transfer	= dquot_transfer,
  	.write_dquot	= dquot_commit,
  	.acquire_dquot	= dquot_acquire,
  	.release_dquot	= dquot_release,
  	.mark_dirty	= dquot_mark_dquot_dirty,

  	.write_info	= dquot_commit_info,
  	.alloc_dquot	= dquot_alloc,
  	.destroy_dquot	= dquot_destroy,

  };

  /*
   * Turn quota off on a device. type == -1 ==> quotaoff for all types (umount)
   */

  int vfs_quota_disable(struct super_block *sb, int type, unsigned int flags)

  {

  	int cnt, ret = 0;

  	struct quota_info *dqopt = sb_dqopt(sb);
  	struct inode *toputinode[MAXQUOTAS];

  	/* Cannot turn off usage accounting without turning off limits, or
  	 * suspend quotas and simultaneously turn quotas off. */
  	if ((flags & DQUOT_USAGE_ENABLED && !(flags & DQUOT_LIMITS_ENABLED))
  	    || (flags & DQUOT_SUSPENDED && flags & (DQUOT_LIMITS_ENABLED |
  	    DQUOT_USAGE_ENABLED)))
  		return -EINVAL;

  	/* We need to serialize quota_off() for device */

  	mutex_lock(&dqopt->dqonoff_mutex);

  
  	/*
  	 * Skip everything if there's nothing to do. We have to do this because
  	 * sometimes we are called when fill_super() failed and calling
  	 * sync_fs() in such cases does no good.
  	 */

  	if (!sb_any_quota_loaded(sb)) {

  		mutex_unlock(&dqopt->dqonoff_mutex);
  		return 0;
  	}

  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  		toputinode[cnt] = NULL;

  		if (type != -1 && cnt != type)
  			continue;

  		if (!sb_has_quota_loaded(sb, cnt))

  			continue;

  
  		if (flags & DQUOT_SUSPENDED) {

  			spin_lock(&dq_state_lock);

  			dqopt->flags |=
  				dquot_state_flag(DQUOT_SUSPENDED, cnt);

  			spin_unlock(&dq_state_lock);

  		} else {

  			spin_lock(&dq_state_lock);

  			dqopt->flags &= ~dquot_state_flag(flags, cnt);
  			/* Turning off suspended quotas? */
  			if (!sb_has_quota_loaded(sb, cnt) &&
  			    sb_has_quota_suspended(sb, cnt)) {
  				dqopt->flags &=	~dquot_state_flag(
  							DQUOT_SUSPENDED, cnt);

  				spin_unlock(&dq_state_lock);

  				iput(dqopt->files[cnt]);
  				dqopt->files[cnt] = NULL;
  				continue;
  			}

  			spin_unlock(&dq_state_lock);

  		}

  
  		/* We still have to keep quota loaded? */
  		if (sb_has_quota_loaded(sb, cnt) && !(flags & DQUOT_SUSPENDED))

  			continue;

  
  		/* Note: these are blocking operations */
  		drop_dquot_ref(sb, cnt);
  		invalidate_dquots(sb, cnt);
  		/*
  		 * Now all dquots should be invalidated, all writes done so we should be only
  		 * users of the info. No locks needed.
  		 */
  		if (info_dirty(&dqopt->info[cnt]))
  			sb->dq_op->write_info(sb, cnt);
  		if (dqopt->ops[cnt]->free_file_info)
  			dqopt->ops[cnt]->free_file_info(sb, cnt);
  		put_quota_format(dqopt->info[cnt].dqi_format);
  
  		toputinode[cnt] = dqopt->files[cnt];

  		if (!sb_has_quota_loaded(sb, cnt))

  			dqopt->files[cnt] = NULL;

  		dqopt->info[cnt].dqi_flags = 0;
  		dqopt->info[cnt].dqi_igrace = 0;
  		dqopt->info[cnt].dqi_bgrace = 0;
  		dqopt->ops[cnt] = NULL;
  	}

  	mutex_unlock(&dqopt->dqonoff_mutex);

  
  	/* Skip syncing and setting flags if quota files are hidden */
  	if (dqopt->flags & DQUOT_QUOTA_SYS_FILE)
  		goto put_inodes;

  	/* Sync the superblock so that buffers with quota data are written to

  	 * disk (and so userspace sees correct data afterwards). */

  	if (sb->s_op->sync_fs)
  		sb->s_op->sync_fs(sb, 1);
  	sync_blockdev(sb->s_bdev);
  	/* Now the quota files are just ordinary files and we can set the
  	 * inode flags back. Moreover we discard the pagecache so that
  	 * userspace sees the writes we did bypassing the pagecache. We
  	 * must also discard the blockdev buffers so that we see the
  	 * changes done by userspace on the next quotaon() */
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
  		if (toputinode[cnt]) {

  			mutex_lock(&dqopt->dqonoff_mutex);

  			/* If quota was reenabled in the meantime, we have
  			 * nothing to do */

  			if (!sb_has_quota_loaded(sb, cnt)) {

  				mutex_lock_nested(&toputinode[cnt]->i_mutex, I_MUTEX_QUOTA);

  				toputinode[cnt]->i_flags &= ~(S_IMMUTABLE |
  				  S_NOATIME | S_NOQUOTA);
  				truncate_inode_pages(&toputinode[cnt]->i_data, 0);

  				mutex_unlock(&toputinode[cnt]->i_mutex);

  				mark_inode_dirty(toputinode[cnt]);

  			}

  			mutex_unlock(&dqopt->dqonoff_mutex);

  		}
  	if (sb->s_bdev)
  		invalidate_bdev(sb->s_bdev);
  put_inodes:
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
  		if (toputinode[cnt]) {

  			/* On remount RO, we keep the inode pointer so that we

  			 * can reenable quota on the subsequent remount RW. We
  			 * have to check 'flags' variable and not use sb_has_
  			 * function because another quotaon / quotaoff could
  			 * change global state before we got here. We refuse
  			 * to suspend quotas when there is pending delete on
  			 * the quota file... */
  			if (!(flags & DQUOT_SUSPENDED))

  				iput(toputinode[cnt]);
  			else if (!toputinode[cnt]->i_nlink)
  				ret = -EBUSY;

  		}

  	return ret;

  }

  int vfs_quota_off(struct super_block *sb, int type, int remount)
  {
  	return vfs_quota_disable(sb, type, remount ? DQUOT_SUSPENDED :
  				 (DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED));
  }

  /*
   *	Turn quotas on on a device
   */

  /*
   * Helper function to turn quotas on when we already have the inode of
   * quota file and no quota information is loaded.
   */
  static int vfs_load_quota_inode(struct inode *inode, int type, int format_id,
  	unsigned int flags)

  {
  	struct quota_format_type *fmt = find_quota_format(format_id);
  	struct super_block *sb = inode->i_sb;
  	struct quota_info *dqopt = sb_dqopt(sb);
  	int error;
  	int oldflags = -1;
  
  	if (!fmt)
  		return -ESRCH;
  	if (!S_ISREG(inode->i_mode)) {
  		error = -EACCES;
  		goto out_fmt;
  	}
  	if (IS_RDONLY(inode)) {
  		error = -EROFS;
  		goto out_fmt;
  	}
  	if (!sb->s_op->quota_write || !sb->s_op->quota_read) {
  		error = -EINVAL;
  		goto out_fmt;
  	}

  	/* Usage always has to be set... */
  	if (!(flags & DQUOT_USAGE_ENABLED)) {
  		error = -EINVAL;
  		goto out_fmt;
  	}

  	if (!(dqopt->flags & DQUOT_QUOTA_SYS_FILE)) {
  		/* As we bypass the pagecache we must now flush the inode so
  		 * that we see all the changes from userspace... */
  		write_inode_now(inode, 1);
  		/* And now flush the block cache so that kernel sees the
  		 * changes */
  		invalidate_bdev(sb->s_bdev);
  	}

  	mutex_lock(&inode->i_mutex);

  	mutex_lock(&dqopt->dqonoff_mutex);

  	if (sb_has_quota_loaded(sb, type)) {

  		error = -EBUSY;
  		goto out_lock;
  	}

  
  	if (!(dqopt->flags & DQUOT_QUOTA_SYS_FILE)) {
  		/* We don't want quota and atime on quota files (deadlocks
  		 * possible) Also nobody should write to the file - we use
  		 * special IO operations which ignore the immutable bit. */
  		down_write(&dqopt->dqptr_sem);
  		oldflags = inode->i_flags & (S_NOATIME | S_IMMUTABLE | S_NOQUOTA);
  		inode->i_flags |= S_NOQUOTA | S_NOATIME | S_IMMUTABLE;
  		up_write(&dqopt->dqptr_sem);
  		sb->dq_op->drop(inode);
  	}

  
  	error = -EIO;
  	dqopt->files[type] = igrab(inode);
  	if (!dqopt->files[type])
  		goto out_lock;
  	error = -EINVAL;
  	if (!fmt->qf_ops->check_quota_file(sb, type))
  		goto out_file_init;
  
  	dqopt->ops[type] = fmt->qf_ops;
  	dqopt->info[type].dqi_format = fmt;

  	dqopt->info[type].dqi_fmt_id = format_id;

  	INIT_LIST_HEAD(&dqopt->info[type].dqi_dirty_list);

  	mutex_lock(&dqopt->dqio_mutex);

  	if ((error = dqopt->ops[type]->read_file_info(sb, type)) < 0) {

  		mutex_unlock(&dqopt->dqio_mutex);

  		goto out_file_init;
  	}

  	mutex_unlock(&dqopt->dqio_mutex);

  	mutex_unlock(&inode->i_mutex);

  	spin_lock(&dq_state_lock);

  	dqopt->flags |= dquot_state_flag(flags, type);

  	spin_unlock(&dq_state_lock);

  
  	add_dquot_ref(sb, type);

  	mutex_unlock(&dqopt->dqonoff_mutex);

  
  	return 0;
  
  out_file_init:
  	dqopt->files[type] = NULL;
  	iput(inode);
  out_lock:

  	mutex_unlock(&dqopt->dqonoff_mutex);

  	if (oldflags != -1) {
  		down_write(&dqopt->dqptr_sem);
  		/* Set the flags back (in the case of accidental quotaon()
  		 * on a wrong file we don't want to mess up the flags) */
  		inode->i_flags &= ~(S_NOATIME | S_NOQUOTA | S_IMMUTABLE);
  		inode->i_flags |= oldflags;
  		up_write(&dqopt->dqptr_sem);
  	}

  	mutex_unlock(&inode->i_mutex);

  out_fmt:
  	put_quota_format(fmt);
  
  	return error; 
  }

  /* Reenable quotas on remount RW */
  static int vfs_quota_on_remount(struct super_block *sb, int type)
  {
  	struct quota_info *dqopt = sb_dqopt(sb);
  	struct inode *inode;
  	int ret;

  	unsigned int flags;

  
  	mutex_lock(&dqopt->dqonoff_mutex);
  	if (!sb_has_quota_suspended(sb, type)) {
  		mutex_unlock(&dqopt->dqonoff_mutex);
  		return 0;
  	}

  	inode = dqopt->files[type];
  	dqopt->files[type] = NULL;

  	spin_lock(&dq_state_lock);

  	flags = dqopt->flags & dquot_state_flag(DQUOT_USAGE_ENABLED |
  						DQUOT_LIMITS_ENABLED, type);
  	dqopt->flags &= ~dquot_state_flag(DQUOT_STATE_FLAGS, type);

  	spin_unlock(&dq_state_lock);

  	mutex_unlock(&dqopt->dqonoff_mutex);

  	flags = dquot_generic_flag(flags, type);
  	ret = vfs_load_quota_inode(inode, type, dqopt->info[type].dqi_fmt_id,
  				   flags);

  	iput(inode);
  
  	return ret;
  }

  int vfs_quota_on_path(struct super_block *sb, int type, int format_id,
  		      struct path *path)
  {
  	int error = security_quota_on(path->dentry);
  	if (error)
  		return error;
  	/* Quota file not on the same filesystem? */
  	if (path->mnt->mnt_sb != sb)
  		error = -EXDEV;
  	else

  		error = vfs_load_quota_inode(path->dentry->d_inode, type,
  					     format_id, DQUOT_USAGE_ENABLED |
  					     DQUOT_LIMITS_ENABLED);

  	return error;
  }

  int vfs_quota_on(struct super_block *sb, int type, int format_id, char *name,

  		 int remount)

  {

  	struct path path;

  	int error;

  	if (remount)
  		return vfs_quota_on_remount(sb, type);

  	error = kern_path(name, LOOKUP_FOLLOW, &path);

  	if (!error) {

  		error = vfs_quota_on_path(sb, type, format_id, &path);
  		path_put(&path);

  	}

  	return error;
  }
  
  /*

   * More powerful function for turning on quotas allowing setting
   * of individual quota flags
   */
  int vfs_quota_enable(struct inode *inode, int type, int format_id,
  		unsigned int flags)
  {
  	int ret = 0;
  	struct super_block *sb = inode->i_sb;
  	struct quota_info *dqopt = sb_dqopt(sb);
  
  	/* Just unsuspend quotas? */
  	if (flags & DQUOT_SUSPENDED)
  		return vfs_quota_on_remount(sb, type);
  	if (!flags)
  		return 0;
  	/* Just updating flags needed? */
  	if (sb_has_quota_loaded(sb, type)) {
  		mutex_lock(&dqopt->dqonoff_mutex);
  		/* Now do a reliable test... */
  		if (!sb_has_quota_loaded(sb, type)) {
  			mutex_unlock(&dqopt->dqonoff_mutex);
  			goto load_quota;
  		}
  		if (flags & DQUOT_USAGE_ENABLED &&
  		    sb_has_quota_usage_enabled(sb, type)) {
  			ret = -EBUSY;
  			goto out_lock;
  		}
  		if (flags & DQUOT_LIMITS_ENABLED &&
  		    sb_has_quota_limits_enabled(sb, type)) {
  			ret = -EBUSY;
  			goto out_lock;
  		}

  		spin_lock(&dq_state_lock);

  		sb_dqopt(sb)->flags |= dquot_state_flag(flags, type);

  		spin_unlock(&dq_state_lock);

  out_lock:
  		mutex_unlock(&dqopt->dqonoff_mutex);
  		return ret;
  	}
  
  load_quota:
  	return vfs_load_quota_inode(inode, type, format_id, flags);
  }
  
  /*

   * This function is used when filesystem needs to initialize quotas
   * during mount time.
   */

  int vfs_quota_on_mount(struct super_block *sb, char *qf_name,
  		int format_id, int type)

  {

  	struct dentry *dentry;

  	int error;

  	dentry = lookup_one_len(qf_name, sb->s_root, strlen(qf_name));

  	if (IS_ERR(dentry))
  		return PTR_ERR(dentry);

  	if (!dentry->d_inode) {
  		error = -ENOENT;
  		goto out;
  	}

  	error = security_quota_on(dentry);

  	if (!error)

  		error = vfs_load_quota_inode(dentry->d_inode, type, format_id,
  				DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);

  out:

  	dput(dentry);
  	return error;

  }

  /* Wrapper to turn on quotas when remounting rw */
  int vfs_dq_quota_on_remount(struct super_block *sb)
  {
  	int cnt;
  	int ret = 0, err;
  
  	if (!sb->s_qcop || !sb->s_qcop->quota_on)
  		return -ENOSYS;
  	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
  		err = sb->s_qcop->quota_on(sb, cnt, 0, NULL, 1);
  		if (err < 0 && !ret)
  			ret = err;
  	}
  	return ret;
  }

  static inline qsize_t qbtos(qsize_t blocks)
  {
  	return blocks << QIF_DQBLKSIZE_BITS;
  }
  
  static inline qsize_t stoqb(qsize_t space)
  {
  	return (space + QIF_DQBLKSIZE - 1) >> QIF_DQBLKSIZE_BITS;
  }

  /* Generic routine for getting common part of quota structure */
  static void do_get_dqblk(struct dquot *dquot, struct if_dqblk *di)
  {
  	struct mem_dqblk *dm = &dquot->dq_dqb;
  
  	spin_lock(&dq_data_lock);

  	di->dqb_bhardlimit = stoqb(dm->dqb_bhardlimit);
  	di->dqb_bsoftlimit = stoqb(dm->dqb_bsoftlimit);

  	di->dqb_curspace = dm->dqb_curspace;
  	di->dqb_ihardlimit = dm->dqb_ihardlimit;
  	di->dqb_isoftlimit = dm->dqb_isoftlimit;
  	di->dqb_curinodes = dm->dqb_curinodes;
  	di->dqb_btime = dm->dqb_btime;
  	di->dqb_itime = dm->dqb_itime;
  	di->dqb_valid = QIF_ALL;
  	spin_unlock(&dq_data_lock);
  }
  
  int vfs_get_dqblk(struct super_block *sb, int type, qid_t id, struct if_dqblk *di)
  {
  	struct dquot *dquot;

  	dquot = dqget(sb, id, type);
  	if (dquot == NODQUOT)

  		return -ESRCH;

  	do_get_dqblk(dquot, di);
  	dqput(dquot);

  	return 0;
  }
  
  /* Generic routine for setting common part of quota structure */

  static int do_set_dqblk(struct dquot *dquot, struct if_dqblk *di)

  {
  	struct mem_dqblk *dm = &dquot->dq_dqb;
  	int check_blim = 0, check_ilim = 0;

  	struct mem_dqinfo *dqi = &sb_dqopt(dquot->dq_sb)->info[dquot->dq_type];
  
  	if ((di->dqb_valid & QIF_BLIMITS &&
  	     (di->dqb_bhardlimit > dqi->dqi_maxblimit ||
  	      di->dqb_bsoftlimit > dqi->dqi_maxblimit)) ||
  	    (di->dqb_valid & QIF_ILIMITS &&
  	     (di->dqb_ihardlimit > dqi->dqi_maxilimit ||
  	      di->dqb_isoftlimit > dqi->dqi_maxilimit)))
  		return -ERANGE;

  
  	spin_lock(&dq_data_lock);
  	if (di->dqb_valid & QIF_SPACE) {
  		dm->dqb_curspace = di->dqb_curspace;
  		check_blim = 1;

  		__set_bit(DQ_LASTSET_B + QIF_SPACE_B, &dquot->dq_flags);

  	}
  	if (di->dqb_valid & QIF_BLIMITS) {

  		dm->dqb_bsoftlimit = qbtos(di->dqb_bsoftlimit);
  		dm->dqb_bhardlimit = qbtos(di->dqb_bhardlimit);

  		check_blim = 1;

  		__set_bit(DQ_LASTSET_B + QIF_BLIMITS_B, &dquot->dq_flags);

  	}
  	if (di->dqb_valid & QIF_INODES) {
  		dm->dqb_curinodes = di->dqb_curinodes;
  		check_ilim = 1;

  		__set_bit(DQ_LASTSET_B + QIF_INODES_B, &dquot->dq_flags);

  	}
  	if (di->dqb_valid & QIF_ILIMITS) {
  		dm->dqb_isoftlimit = di->dqb_isoftlimit;
  		dm->dqb_ihardlimit = di->dqb_ihardlimit;
  		check_ilim = 1;

  		__set_bit(DQ_LASTSET_B + QIF_ILIMITS_B, &dquot->dq_flags);

  	}

  	if (di->dqb_valid & QIF_BTIME) {

  		dm->dqb_btime = di->dqb_btime;

  		check_blim = 1;

  		__set_bit(DQ_LASTSET_B + QIF_BTIME_B, &dquot->dq_flags);
  	}
  	if (di->dqb_valid & QIF_ITIME) {

  		dm->dqb_itime = di->dqb_itime;

  		check_ilim = 1;

  		__set_bit(DQ_LASTSET_B + QIF_ITIME_B, &dquot->dq_flags);
  	}

  
  	if (check_blim) {

  		if (!dm->dqb_bsoftlimit || dm->dqb_curspace < dm->dqb_bsoftlimit) {

  			dm->dqb_btime = 0;
  			clear_bit(DQ_BLKS_B, &dquot->dq_flags);
  		}
  		else if (!(di->dqb_valid & QIF_BTIME))	/* Set grace only if user hasn't provided his own... */

  			dm->dqb_btime = get_seconds() + dqi->dqi_bgrace;

  	}
  	if (check_ilim) {
  		if (!dm->dqb_isoftlimit || dm->dqb_curinodes < dm->dqb_isoftlimit) {
  			dm->dqb_itime = 0;
  			clear_bit(DQ_INODES_B, &dquot->dq_flags);
  		}
  		else if (!(di->dqb_valid & QIF_ITIME))	/* Set grace only if user hasn't provided his own... */

  			dm->dqb_itime = get_seconds() + dqi->dqi_igrace;

  	}
  	if (dm->dqb_bhardlimit || dm->dqb_bsoftlimit || dm->dqb_ihardlimit || dm->dqb_isoftlimit)
  		clear_bit(DQ_FAKE_B, &dquot->dq_flags);
  	else
  		set_bit(DQ_FAKE_B, &dquot->dq_flags);
  	spin_unlock(&dq_data_lock);
  	mark_dquot_dirty(dquot);

  
  	return 0;

  }
  
  int vfs_set_dqblk(struct super_block *sb, int type, qid_t id, struct if_dqblk *di)
  {
  	struct dquot *dquot;

  	int rc;

  	dquot = dqget(sb, id, type);
  	if (!dquot) {
  		rc = -ESRCH;
  		goto out;

  	}

  	rc = do_set_dqblk(dquot, di);

  	dqput(dquot);

  out:

  	return rc;

  }
  
  /* Generic routine for getting common part of quota file information */
  int vfs_get_dqinfo(struct super_block *sb, int type, struct if_dqinfo *ii)
  {
  	struct mem_dqinfo *mi;
    

  	mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);

  	if (!sb_has_quota_active(sb, type)) {

  		mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);

  		return -ESRCH;
  	}
  	mi = sb_dqopt(sb)->info + type;
  	spin_lock(&dq_data_lock);
  	ii->dqi_bgrace = mi->dqi_bgrace;
  	ii->dqi_igrace = mi->dqi_igrace;
  	ii->dqi_flags = mi->dqi_flags & DQF_MASK;
  	ii->dqi_valid = IIF_ALL;
  	spin_unlock(&dq_data_lock);

  	mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);

  	return 0;
  }
  
  /* Generic routine for setting common part of quota file information */
  int vfs_set_dqinfo(struct super_block *sb, int type, struct if_dqinfo *ii)
  {
  	struct mem_dqinfo *mi;

  	int err = 0;

  	mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);

  	if (!sb_has_quota_active(sb, type)) {
  		err = -ESRCH;
  		goto out;

  	}
  	mi = sb_dqopt(sb)->info + type;
  	spin_lock(&dq_data_lock);
  	if (ii->dqi_valid & IIF_BGRACE)
  		mi->dqi_bgrace = ii->dqi_bgrace;
  	if (ii->dqi_valid & IIF_IGRACE)
  		mi->dqi_igrace = ii->dqi_igrace;
  	if (ii->dqi_valid & IIF_FLAGS)
  		mi->dqi_flags = (mi->dqi_flags & ~DQF_MASK) | (ii->dqi_flags & DQF_MASK);
  	spin_unlock(&dq_data_lock);
  	mark_info_dirty(sb, type);
  	/* Force write to disk */
  	sb->dq_op->write_info(sb, type);

  out:

  	mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);

  	return err;

  }
  
  struct quotactl_ops vfs_quotactl_ops = {
  	.quota_on	= vfs_quota_on,
  	.quota_off	= vfs_quota_off,
  	.quota_sync	= vfs_quota_sync,
  	.get_info	= vfs_get_dqinfo,
  	.set_info	= vfs_set_dqinfo,
  	.get_dqblk	= vfs_get_dqblk,
  	.set_dqblk	= vfs_set_dqblk
  };
  
  static ctl_table fs_dqstats_table[] = {
  	{
  		.ctl_name	= FS_DQ_LOOKUPS,
  		.procname	= "lookups",
  		.data		= &dqstats.lookups,
  		.maxlen		= sizeof(int),
  		.mode		= 0444,
  		.proc_handler	= &proc_dointvec,
  	},
  	{
  		.ctl_name	= FS_DQ_DROPS,
  		.procname	= "drops",
  		.data		= &dqstats.drops,
  		.maxlen		= sizeof(int),
  		.mode		= 0444,
  		.proc_handler	= &proc_dointvec,
  	},
  	{
  		.ctl_name	= FS_DQ_READS,
  		.procname	= "reads",
  		.data		= &dqstats.reads,
  		.maxlen		= sizeof(int),
  		.mode		= 0444,
  		.proc_handler	= &proc_dointvec,
  	},
  	{
  		.ctl_name	= FS_DQ_WRITES,
  		.procname	= "writes",
  		.data		= &dqstats.writes,
  		.maxlen		= sizeof(int),
  		.mode		= 0444,
  		.proc_handler	= &proc_dointvec,
  	},
  	{
  		.ctl_name	= FS_DQ_CACHE_HITS,
  		.procname	= "cache_hits",
  		.data		= &dqstats.cache_hits,
  		.maxlen		= sizeof(int),
  		.mode		= 0444,
  		.proc_handler	= &proc_dointvec,
  	},
  	{
  		.ctl_name	= FS_DQ_ALLOCATED,
  		.procname	= "allocated_dquots",
  		.data		= &dqstats.allocated_dquots,
  		.maxlen		= sizeof(int),
  		.mode		= 0444,
  		.proc_handler	= &proc_dointvec,
  	},
  	{
  		.ctl_name	= FS_DQ_FREE,
  		.procname	= "free_dquots",
  		.data		= &dqstats.free_dquots,
  		.maxlen		= sizeof(int),
  		.mode		= 0444,
  		.proc_handler	= &proc_dointvec,
  	},
  	{
  		.ctl_name	= FS_DQ_SYNCS,
  		.procname	= "syncs",
  		.data		= &dqstats.syncs,
  		.maxlen		= sizeof(int),
  		.mode		= 0444,
  		.proc_handler	= &proc_dointvec,
  	},

  #ifdef CONFIG_PRINT_QUOTA_WARNING

  	{
  		.ctl_name	= FS_DQ_WARNINGS,
  		.procname	= "warnings",
  		.data		= &flag_print_warnings,
  		.maxlen		= sizeof(int),
  		.mode		= 0644,
  		.proc_handler	= &proc_dointvec,
  	},

  #endif

  	{ .ctl_name = 0 },
  };
  
  static ctl_table fs_table[] = {
  	{
  		.ctl_name	= FS_DQSTATS,
  		.procname	= "quota",
  		.mode		= 0555,
  		.child		= fs_dqstats_table,
  	},
  	{ .ctl_name = 0 },
  };
  
  static ctl_table sys_table[] = {
  	{
  		.ctl_name	= CTL_FS,
  		.procname	= "fs",
  		.mode		= 0555,
  		.child		= fs_table,
  	},
  	{ .ctl_name = 0 },
  };
  
  static int __init dquot_init(void)
  {
  	int i;
  	unsigned long nr_hash, order;
  
  	printk(KERN_NOTICE "VFS: Disk quotas %s
  ", __DQUOT_VERSION__);

  	register_sysctl_table(sys_table);

  	dquot_cachep = kmem_cache_create("dquot",

  			sizeof(struct dquot), sizeof(unsigned long) * 4,

  			(SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
  				SLAB_MEM_SPREAD|SLAB_PANIC),

  			NULL);

  
  	order = 0;
  	dquot_hash = (struct hlist_head *)__get_free_pages(GFP_ATOMIC, order);
  	if (!dquot_hash)
  		panic("Cannot create dquot hash table");
  
  	/* Find power-of-two hlist_heads which can fit into allocation */
  	nr_hash = (1UL << order) * PAGE_SIZE / sizeof(struct hlist_head);
  	dq_hash_bits = 0;
  	do {
  		dq_hash_bits++;
  	} while (nr_hash >> dq_hash_bits);
  	dq_hash_bits--;
  
  	nr_hash = 1UL << dq_hash_bits;
  	dq_hash_mask = nr_hash - 1;
  	for (i = 0; i < nr_hash; i++)
  		INIT_HLIST_HEAD(dquot_hash + i);
  
  	printk("Dquot-cache hash table entries: %ld (order %ld, %ld bytes)
  ",
  			nr_hash, order, (PAGE_SIZE << order));

  	register_shrinker(&dqcache_shrinker);

  #ifdef CONFIG_QUOTA_NETLINK_INTERFACE
  	if (genl_register_family(&quota_genl_family) != 0)
  		printk(KERN_ERR "VFS: Failed to create quota netlink interface.
  ");
  #endif

  	return 0;
  }
  module_init(dquot_init);
  
  EXPORT_SYMBOL(register_quota_format);
  EXPORT_SYMBOL(unregister_quota_format);
  EXPORT_SYMBOL(dqstats);
  EXPORT_SYMBOL(dq_data_lock);

  EXPORT_SYMBOL(vfs_quota_enable);

  EXPORT_SYMBOL(vfs_quota_on);

  EXPORT_SYMBOL(vfs_quota_on_path);

  EXPORT_SYMBOL(vfs_quota_on_mount);

  EXPORT_SYMBOL(vfs_quota_disable);

  EXPORT_SYMBOL(vfs_quota_off);

  EXPORT_SYMBOL(dquot_scan_active);

  EXPORT_SYMBOL(vfs_quota_sync);
  EXPORT_SYMBOL(vfs_get_dqinfo);
  EXPORT_SYMBOL(vfs_set_dqinfo);
  EXPORT_SYMBOL(vfs_get_dqblk);
  EXPORT_SYMBOL(vfs_set_dqblk);
  EXPORT_SYMBOL(dquot_commit);
  EXPORT_SYMBOL(dquot_commit_info);
  EXPORT_SYMBOL(dquot_acquire);
  EXPORT_SYMBOL(dquot_release);
  EXPORT_SYMBOL(dquot_mark_dquot_dirty);
  EXPORT_SYMBOL(dquot_initialize);
  EXPORT_SYMBOL(dquot_drop);

  EXPORT_SYMBOL(vfs_dq_drop);

  EXPORT_SYMBOL(dqget);
  EXPORT_SYMBOL(dqput);

  EXPORT_SYMBOL(dquot_alloc_space);
  EXPORT_SYMBOL(dquot_alloc_inode);
  EXPORT_SYMBOL(dquot_free_space);
  EXPORT_SYMBOL(dquot_free_inode);
  EXPORT_SYMBOL(dquot_transfer);

  EXPORT_SYMBOL(vfs_dq_transfer);
  EXPORT_SYMBOL(vfs_dq_quota_on_remount);