/*
 * 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. Currently only the
 * ext2 filesystem has support for disk quotas. Other filesystems may
 * be added in the future. 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.
 * 
 * Version: $Id: dquot.c,v 6.3 1996/11/17 18:35:34 mvw Exp mvw $
 * 
 * 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 dquots with dq_count > 0 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
 *
 * (C) Copyright 1994 - 1997 Marco van Wieringen 
 */

#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/sched.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/smp_lock.h>
#include <linux/init.h>

#include <asm/uaccess.h>

#define __DQUOT_VERSION__       "dquot_6.4.0"

int nr_dquots, nr_free_dquots;

static char *quotatypes[] = INITQFNAMES;

static inline struct quota_mount_options *sb_dqopt(struct super_block *sb)
{
        return &sb->s_dquot;
}

/*
 * 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 the sync and invalidate operations, 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
 * nr_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.
 */

/*
 * Note that any operation which operates on dquot data (ie. dq_dqb) mustn't
 * block while it's updating/reading it. Otherwise races would occur.
 *
 * Locked dquots might not be referenced in inodes - operations like
 * add_dquot_space() does dqduplicate() and would complain. Currently
 * dquot it locked only once in its existence - when it's being read
 * to memory on first dqget() and at that time it can't be referenced
 * from inode. Write operations on dquots don't hold dquot lock as they
 * copy data to internal buffers before writing anyway and copying as well
 * as any data update should be atomic. Also nobody can change used
 * entries in dquot structure as this is done only when quota is destroyed
 * and invalidate_dquots() waits for dquot to have dq_count == 0.
 */

static LIST_HEAD(inuse_list);
static LIST_HEAD(free_dquots);
static struct list_head dquot_hash[NR_DQHASH];

static struct dqstats dqstats;

static void dqput(struct dquot *);
static struct dquot *dqduplicate(struct dquot *);

static inline char is_enabled(struct quota_mount_options *dqopt, short type)
{
        switch (type) {
                case USRQUOTA:
                        return((dqopt->flags & DQUOT_USR_ENABLED) != 0);
                case GRPQUOTA:
                        return((dqopt->flags & DQUOT_GRP_ENABLED) != 0);
        }
        return(0);
}

static inline char sb_has_quota_enabled(struct super_block *sb, short type)
{
        return is_enabled(sb_dqopt(sb), type);
}

static inline int const hashfn(kdev_t dev, unsigned int id, short type)
{
        return((HASHDEV(dev) ^ id) * (MAXQUOTAS - type)) % NR_DQHASH;
}

static inline void insert_dquot_hash(struct dquot *dquot)
{
        struct list_head *head = dquot_hash + hashfn(dquot->dq_dev, dquot->dq_id, dquot->dq_type);
        list_add(&dquot->dq_hash, head);
}

static inline void remove_dquot_hash(struct dquot *dquot)
{
        list_del(&dquot->dq_hash);
        INIT_LIST_HEAD(&dquot->dq_hash);
}

static inline struct dquot *find_dquot(unsigned int hashent, kdev_t dev, unsigned int id, short type)
{
        struct list_head *head;
        struct dquot *dquot;

        for (head = dquot_hash[hashent].next; head != dquot_hash+hashent; head = head->next) {
                dquot = list_entry(head, struct dquot, dq_hash);
                if (dquot->dq_dev == dev && dquot->dq_id == id && dquot->dq_type == type)
                        return dquot;
        }
        return NODQUOT;
}

/* Add a dquot to the head of the free list */
static inline void put_dquot_head(struct dquot *dquot)
{
        list_add(&dquot->dq_free, &free_dquots);
        nr_free_dquots++;
}

/* Add a dquot to the tail of the free list */
static inline void put_dquot_last(struct dquot *dquot)
{
        list_add(&dquot->dq_free, free_dquots.prev);
        nr_free_dquots++;
}

/* Move dquot to the head of free list (it must be already on it) */
static inline void move_dquot_head(struct dquot *dquot)
{
        list_del(&dquot->dq_free);
        list_add(&dquot->dq_free, &free_dquots);
}

static inline void remove_free_dquot(struct dquot *dquot)
{
        if (list_empty(&dquot->dq_free))
                return;
        list_del(&dquot->dq_free);
        INIT_LIST_HEAD(&dquot->dq_free);
        nr_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(&dquot->dq_inuse, inuse_list.prev);
        nr_dquots++;
}

static inline void remove_inuse(struct dquot *dquot)
{
        nr_dquots--;
        list_del(&dquot->dq_inuse);
}

static void __wait_on_dquot(struct dquot *dquot)
{
        DECLARE_WAITQUEUE(wait, current);

        add_wait_queue(&dquot->dq_wait_lock, &wait);
repeat:
        set_current_state(TASK_UNINTERRUPTIBLE);
        if (dquot->dq_flags & DQ_LOCKED) {
                schedule();
                goto repeat;
        }
        remove_wait_queue(&dquot->dq_wait_lock, &wait);
        current->state = TASK_RUNNING;
}

static inline void wait_on_dquot(struct dquot *dquot)
{
        if (dquot->dq_flags & DQ_LOCKED)
                __wait_on_dquot(dquot);
}

static inline void lock_dquot(struct dquot *dquot)
{
        wait_on_dquot(dquot);
        dquot->dq_flags |= DQ_LOCKED;
}

static inline void unlock_dquot(struct dquot *dquot)
{
        dquot->dq_flags &= ~DQ_LOCKED;
        wake_up(&dquot->dq_wait_lock);
}

static void __wait_dquot_unused(struct dquot *dquot)
{
        DECLARE_WAITQUEUE(wait, current);

        add_wait_queue(&dquot->dq_wait_free, &wait);
repeat:
        set_current_state(TASK_UNINTERRUPTIBLE);
        if (dquot->dq_count) {
                schedule();
                goto repeat;
        }
        remove_wait_queue(&dquot->dq_wait_free, &wait);
        current->state = TASK_RUNNING;
}

/*
 *      We don't have to be afraid of deadlocks as we never have quotas on quota files...
 */
static void write_dquot(struct dquot *dquot)
{
        short type = dquot->dq_type;
        struct file *filp;
        mm_segment_t fs;
        loff_t offset;
        ssize_t ret;
        struct semaphore *sem = &dquot->dq_sb->s_dquot.dqio_sem;
        struct dqblk dqbuf;

        down(sem);
        filp = dquot->dq_sb->s_dquot.files[type];
        offset = dqoff(dquot->dq_id);
        fs = get_fs();
        set_fs(KERNEL_DS);

        /*
         * Note: clear the DQ_MOD flag unconditionally,
         * so we don't loop forever on failure.
         */
        memcpy(&dqbuf, &dquot->dq_dqb, sizeof(struct dqblk));
        dquot->dq_flags &= ~DQ_MOD;
        ret = 0;
        if (filp)
                ret = filp->f_op->write(filp, (char *)&dqbuf, 
                                        sizeof(struct dqblk), &offset);
        if (ret != sizeof(struct dqblk))
                printk(KERN_WARNING "VFS: dquota write failed on dev %s\n",
                        kdevname(dquot->dq_dev));

        set_fs(fs);
        up(sem);
        dqstats.writes++;
}

static void read_dquot(struct dquot *dquot)
{
        short type = dquot->dq_type;
        struct file *filp;
        mm_segment_t fs;
        loff_t offset;

        filp = dquot->dq_sb->s_dquot.files[type];
        if (filp == (struct file *)NULL)
                return;

        lock_dquot(dquot);
        if (!dquot->dq_sb)      /* Invalidated quota? */
                goto out_lock;
        /* Now we are sure filp is valid - the dquot isn't invalidated */
        down(&dquot->dq_sb->s_dquot.dqio_sem);
        offset = dqoff(dquot->dq_id);
        fs = get_fs();
        set_fs(KERNEL_DS);
        filp->f_op->read(filp, (char *)&dquot->dq_dqb, sizeof(struct dqblk), &offset);
        up(&dquot->dq_sb->s_dquot.dqio_sem);
        set_fs(fs);

        if (dquot->dq_bhardlimit == 0 && dquot->dq_bsoftlimit == 0 &&
            dquot->dq_ihardlimit == 0 && dquot->dq_isoftlimit == 0)
                dquot->dq_flags |= DQ_FAKE;
        dqstats.reads++;
out_lock:
        unlock_dquot(dquot);
}

/* Invalidate all dquots on the list, wait for all users. Note that this function is called
 * after quota is disabled so no new quota might be created. As we only insert to the end of
 * inuse list, we don't have to restart searching... */
static void invalidate_dquots(struct super_block *sb, short type)
{
        struct dquot *dquot;
        struct list_head *head;

restart:
        for (head = inuse_list.next; head != &inuse_list; head = head->next) {
                dquot = list_entry(head, struct dquot, dq_inuse);
                if (dquot->dq_sb != sb)
                        continue;
                if (dquot->dq_type != type)
                        continue;
                dquot->dq_flags |= DQ_INVAL;
                if (dquot->dq_count)
                        /*
                         *  Wait for any users of quota. As we have already cleared the flags in
                         *  superblock and cleared all pointers from inodes we are assured
                         *  that there will be no new users of this quota.
                         */
                        __wait_dquot_unused(dquot);
                /* Quota now have no users and it has been written on last dqput() */
                remove_dquot_hash(dquot);
                remove_free_dquot(dquot);
                remove_inuse(dquot);
                kmem_cache_free(dquot_cachep, dquot);
                goto restart;
        }
}

int sync_dquots(kdev_t dev, short type)
{
        struct list_head *head;
        struct dquot *dquot;

        lock_kernel();
restart:
        for (head = inuse_list.next; head != &inuse_list; head = head->next) {
                dquot = list_entry(head, struct dquot, dq_inuse);
                if (dev && dquot->dq_dev != dev)
                        continue;
                if (type != -1 && dquot->dq_type != type)
                        continue;
                if (!dquot->dq_sb)      /* Invalidated? */
                        continue;
                if (!(dquot->dq_flags & (DQ_MOD | DQ_LOCKED)))
                        continue;
                /* Raise use count so quota won't be invalidated. We can't use dqduplicate() as it does too many tests */
                dquot->dq_count++;
                if (dquot->dq_flags & DQ_LOCKED)
                        wait_on_dquot(dquot);
                if (dquot->dq_flags & DQ_MOD)
                        write_dquot(dquot);
                dqput(dquot);
                goto restart;
        }
        dqstats.syncs++;
        unlock_kernel();
        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);
                kmem_cache_free(dquot_cachep, dquot);
                count--;
                head = free_dquots.prev;
        }
}

int shrink_dqcache_memory(int priority, unsigned int gfp_mask)
{
        lock_kernel();
        prune_dqcache(nr_free_dquots / (priority + 1));
        unlock_kernel();
        return kmem_cache_shrink(dquot_cachep);
}

/* NOTE: If you change this function please check whether dqput_blocks() works right... */
static void dqput(struct dquot *dquot)
{
        if (!dquot)
                return;
        if (!dquot->dq_count) {
                printk("VFS: dqput: trying to free free dquot\n");
                printk("VFS: device %s, dquot of %s %d\n",
                        kdevname(dquot->dq_dev), quotatypes[dquot->dq_type],
                        dquot->dq_id);
                return;
        }

        dqstats.drops++;
we_slept:
        if (dquot->dq_count > 1) {
                /* We have more than one user... We can simply decrement use count */
                dquot->dq_count--;
                return;
        }
        if (dquot->dq_flags & DQ_MOD) {
                write_dquot(dquot);
                goto we_slept;
        }

        /* sanity check */
        if (!list_empty(&dquot->dq_free)) {
                printk(KERN_ERR "dqput: dquot already on free list??\n");
                dquot->dq_count--;      /* J.K. Just decrementing use count seems safer... */
                return;
        }
        dquot->dq_count--;
        /* If dquot is going to be invalidated invalidate_dquots() is going to free it so */
        if (!(dquot->dq_flags & DQ_INVAL))
                put_dquot_last(dquot);  /* Place at end of LRU free queue */
        wake_up(&dquot->dq_wait_free);
}

static struct dquot *get_empty_dquot(void)
{
        struct dquot *dquot;

        dquot = kmem_cache_alloc(dquot_cachep, SLAB_KERNEL);
        if(!dquot)
                return NODQUOT;

        memset((caddr_t)dquot, 0, sizeof(struct dquot));
        init_waitqueue_head(&dquot->dq_wait_free);
        init_waitqueue_head(&dquot->dq_wait_lock);
        INIT_LIST_HEAD(&dquot->dq_free);
        INIT_LIST_HEAD(&dquot->dq_inuse);
        INIT_LIST_HEAD(&dquot->dq_hash);
        dquot->dq_count = 1;
        /* all dquots go on the inuse_list */
        put_inuse(dquot);

        return dquot;
}

static struct dquot *dqget(struct super_block *sb, unsigned int id, short type)
{
        unsigned int hashent = hashfn(sb->s_dev, id, type);
        struct dquot *dquot, *empty = NODQUOT;
        struct quota_mount_options *dqopt = sb_dqopt(sb);

we_slept:
        if (!is_enabled(dqopt, type)) {
                if (empty)
                        dqput(empty);
                return NODQUOT;
        }

        if ((dquot = find_dquot(hashent, sb->s_dev, id, type)) == NODQUOT) {
                if (empty == NODQUOT) {
                        if ((empty = get_empty_dquot()) == NODQUOT)
                                schedule();     /* Try to wait for a moment... */
                        goto we_slept;
                }
                dquot = empty;
                dquot->dq_id = id;
                dquot->dq_type = type;
                dquot->dq_dev = sb->s_dev;
                dquot->dq_sb = sb;
                /* hash it first so it can be found */
                insert_dquot_hash(dquot);
                read_dquot(dquot);
        } else {
                if (!dquot->dq_count++)
                        remove_free_dquot(dquot);
                dqstats.cache_hits++;
                wait_on_dquot(dquot);
                if (empty)
                        dqput(empty);
        }

        if (!dquot->dq_sb) {    /* Has somebody invalidated entry under us? */
                printk(KERN_ERR "VFS: dqget(): Quota invalidated in dqget()!\n");
                dqput(dquot);
                return NODQUOT;
        }
        dquot->dq_referenced++;
        dqstats.lookups++;

        return dquot;
}

static struct dquot *dqduplicate(struct dquot *dquot)
{
        if (dquot == NODQUOT)
                return NODQUOT;
        dquot->dq_count++;
        if (!dquot->dq_sb) {
                printk(KERN_ERR "VFS: dqduplicate(): Invalidated quota to be duplicated!\n");
                dquot->dq_count--;
                return NODQUOT;
        }
        if (dquot->dq_flags & DQ_LOCKED)
                printk(KERN_ERR "VFS: dqduplicate(): Locked quota to be duplicated!\n");
        dquot->dq_referenced++;
        dqstats.lookups++;
        return dquot;
}

static int dqinit_needed(struct inode *inode, short 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;
}

static void add_dquot_ref(struct super_block *sb, short type)
{
        struct list_head *p;

        if (!sb->dq_op)
                return; /* nothing to do */

restart:
        file_list_lock();
        for (p = sb->s_files.next; p != &sb->s_files; p = p->next) {
                struct file *filp = list_entry(p, struct file, f_list);
                struct inode *inode = filp->f_dentry->d_inode;
                if (filp->f_mode & FMODE_WRITE && dqinit_needed(inode, type)) {
                        struct vfsmount *mnt = mntget(filp->f_vfsmnt);
                        struct dentry *dentry = dget(filp->f_dentry);
                        file_list_unlock();
                        sb->dq_op->initialize(inode, type);
                        dput(dentry);
                        mntput(mnt);
                        /* As we may have blocked we had better restart... */
                        goto restart;
                }
        }
        file_list_unlock();
}

/* Return 0 if dqput() won't block (note that 1 doesn't necessarily mean blocking) */
static inline int dqput_blocks(struct dquot *dquot)
{
        if (dquot->dq_count == 1)
                return 1;
        return 0;
}

/* Remove references to dquots from inode - add dquot to list for freeing if needed */
int remove_inode_dquot_ref(struct inode *inode, short type, struct list_head *tofree_head)
{
        struct dquot *dquot = inode->i_dquot[type];
        int cnt;

        inode->i_dquot[type] = NODQUOT;
        /* any other quota in use? */
        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                if (inode->i_dquot[cnt] != NODQUOT)
                        goto put_it;
        }
        inode->i_flags &= ~S_QUOTA;
put_it:
        if (dquot != NODQUOT) {
                if (dqput_blocks(dquot)) {
                        if (dquot->dq_count != 1)
                                printk(KERN_WARNING "VFS: Adding dquot with dq_count %d to dispose list.\n", dquot->dq_count);
                        list_add(&dquot->dq_free, tofree_head); /* As dquot must have currently users it can't be on the free list... */
                        return 1;
                }
                else
                        dqput(dquot);   /* We have guaranteed we won't block */
        }
        return 0;
}

/* Free list of dquots - called from inode.c */
void put_dquot_list(struct list_head *tofree_head)
{
        struct list_head *act_head;
        struct dquot *dquot;

        lock_kernel();
        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(&dquot->dq_free);      /* Remove dquot from the list so we won't have problems... */
                INIT_LIST_HEAD(&dquot->dq_free);
                dqput(dquot);
        }
        unlock_kernel();
}

static inline void dquot_incr_inodes(struct dquot *dquot, unsigned long number)
{
        dquot->dq_curinodes += number;
        dquot->dq_flags |= DQ_MOD;
}

static inline void dquot_incr_blocks(struct dquot *dquot, unsigned long number)
{
        dquot->dq_curblocks += number;
        dquot->dq_flags |= DQ_MOD;
}

static inline void dquot_decr_inodes(struct dquot *dquot, unsigned long number)
{
        if (dquot->dq_curinodes > number)
                dquot->dq_curinodes -= number;
        else
                dquot->dq_curinodes = 0;
        if (dquot->dq_curinodes < dquot->dq_isoftlimit)
                dquot->dq_itime = (time_t) 0;
        dquot->dq_flags &= ~DQ_INODES;
        dquot->dq_flags |= DQ_MOD;
}

static inline void dquot_decr_blocks(struct dquot *dquot, unsigned long number)
{
        if (dquot->dq_curblocks > number)
                dquot->dq_curblocks -= number;
        else
                dquot->dq_curblocks = 0;
        if (dquot->dq_curblocks < dquot->dq_bsoftlimit)
                dquot->dq_btime = (time_t) 0;
        dquot->dq_flags &= ~DQ_BLKS;
        dquot->dq_flags |= DQ_MOD;
}

static inline int need_print_warning(struct dquot *dquot, int flag)
{
        switch (dquot->dq_type) {
                case USRQUOTA:
                        return current->fsuid == dquot->dq_id && !(dquot->dq_flags & flag);
                case GRPQUOTA:
                        return in_group_p(dquot->dq_id) && !(dquot->dq_flags & flag);
        }
        return 0;
}

/* Values of warnings */
#define NOWARN 0
#define IHARDWARN 1
#define ISOFTLONGWARN 2
#define ISOFTWARN 3
#define BHARDWARN 4
#define BSOFTLONGWARN 5
#define BSOFTWARN 6

/* Print warning to user which exceeded quota */
static void print_warning(struct dquot *dquot, const char warntype)
{
        char *msg = NULL;
        int flag = (warntype == BHARDWARN || warntype == BSOFTLONGWARN) ? DQ_BLKS :
          ((warntype == IHARDWARN || warntype == ISOFTLONGWARN) ? DQ_INODES : 0);

        if (!need_print_warning(dquot, flag))
                return;
        dquot->dq_flags |= flag;
        tty_write_message(current->tty, (char *)bdevname(dquot->dq_sb->s_dev));
        if (warntype == ISOFTWARN || warntype == BSOFTWARN)
                tty_write_message(current->tty, ": warning, ");
        else
                tty_write_message(current->tty, ": write failed, ");
        tty_write_message(current->tty, quotatypes[dquot->dq_type]);
        switch (warntype) {
                case IHARDWARN:
                        msg = " file limit reached.\n";
                        break;
                case ISOFTLONGWARN:
                        msg = " file quota exceeded too long.\n";
                        break;
                case ISOFTWARN:
                        msg = " file quota exceeded.\n";
                        break;
                case BHARDWARN:
                        msg = " block limit reached.\n";
                        break;
                case BSOFTLONGWARN:
                        msg = " block quota exceeded too long.\n";
                        break;
                case BSOFTWARN:
                        msg = " block quota exceeded.\n";
                        break;
        }
        tty_write_message(current->tty, msg);
}

static inline void flush_warnings(struct dquot **dquots, char *warntype)
{
        int i;

        for (i = 0; i < MAXQUOTAS; i++)
                if (dquots[i] != NODQUOT && warntype[i] != NOWARN)
                        print_warning(dquots[i], warntype[i]);
}

static inline char ignore_hardlimit(struct dquot *dquot)
{
        return capable(CAP_SYS_RESOURCE) && !dquot->dq_sb->s_dquot.rsquash[dquot->dq_type];
}

static int check_idq(struct dquot *dquot, ulong inodes, char *warntype)
{
        *warntype = NOWARN;
        if (inodes <= 0 || dquot->dq_flags & DQ_FAKE)
                return QUOTA_OK;

        if (dquot->dq_ihardlimit &&
           (dquot->dq_curinodes + inodes) > dquot->dq_ihardlimit &&
            !ignore_hardlimit(dquot)) {
                *warntype = IHARDWARN;
                return NO_QUOTA;
        }

        if (dquot->dq_isoftlimit &&
           (dquot->dq_curinodes + inodes) > dquot->dq_isoftlimit &&
            dquot->dq_itime && CURRENT_TIME >= dquot->dq_itime &&
            !ignore_hardlimit(dquot)) {
                *warntype = ISOFTLONGWARN;
                return NO_QUOTA;
        }

        if (dquot->dq_isoftlimit &&
           (dquot->dq_curinodes + inodes) > dquot->dq_isoftlimit &&
            dquot->dq_itime == 0) {
                *warntype = ISOFTWARN;
                dquot->dq_itime = CURRENT_TIME + dquot->dq_sb->s_dquot.inode_expire[dquot->dq_type];
        }

        return QUOTA_OK;
}

static int check_bdq(struct dquot *dquot, ulong blocks, char prealloc, char *warntype)
{
        *warntype = 0;
        if (blocks <= 0 || dquot->dq_flags & DQ_FAKE)
                return QUOTA_OK;

        if (dquot->dq_bhardlimit &&
           (dquot->dq_curblocks + blocks) > dquot->dq_bhardlimit &&
            !ignore_hardlimit(dquot)) {
                if (!prealloc)
                        *warntype = BHARDWARN;
                return NO_QUOTA;
        }

        if (dquot->dq_bsoftlimit &&
           (dquot->dq_curblocks + blocks) > dquot->dq_bsoftlimit &&
            dquot->dq_btime && CURRENT_TIME >= dquot->dq_btime &&
            !ignore_hardlimit(dquot)) {
                if (!prealloc)
                        *warntype = BSOFTLONGWARN;
                return NO_QUOTA;
        }

        if (dquot->dq_bsoftlimit &&
           (dquot->dq_curblocks + blocks) > dquot->dq_bsoftlimit &&
            dquot->dq_btime == 0) {
                if (!prealloc) {
                        *warntype = BSOFTWARN;
                        dquot->dq_btime = CURRENT_TIME + dquot->dq_sb->s_dquot.block_expire[dquot->dq_type];
                }
                else
                        /*
                         * We don't allow preallocation to exceed softlimit so exceeding will
                         * be always printed
                         */
                        return NO_QUOTA;
        }

        return QUOTA_OK;
}

/*
 * Initialize a dquot-struct with new quota info. This is used by the
 * system call interface functions.
 */ 
static int set_dqblk(struct super_block *sb, int id, short type, int flags, struct dqblk *dqblk)
{
        struct dquot *dquot;
        int error = -EFAULT;
        struct dqblk dq_dqblk;

        if (copy_from_user(&dq_dqblk, dqblk, sizeof(struct dqblk)))
                return error;

        if (sb && (dquot = dqget(sb, id, type)) != NODQUOT) {
                /* We can't block while changing quota structure... */
                if (id > 0 && ((flags & SET_QUOTA) || (flags & SET_QLIMIT))) {
                        dquot->dq_bhardlimit = dq_dqblk.dqb_bhardlimit;
                        dquot->dq_bsoftlimit = dq_dqblk.dqb_bsoftlimit;
                        dquot->dq_ihardlimit = dq_dqblk.dqb_ihardlimit;
                        dquot->dq_isoftlimit = dq_dqblk.dqb_isoftlimit;
                }

                if ((flags & SET_QUOTA) || (flags & SET_USE)) {
                        if (dquot->dq_isoftlimit &&
                            dquot->dq_curinodes < dquot->dq_isoftlimit &&
                            dq_dqblk.dqb_curinodes >= dquot->dq_isoftlimit)
                                dquot->dq_itime = CURRENT_TIME + dquot->dq_sb->s_dquot.inode_expire[type];
                        dquot->dq_curinodes = dq_dqblk.dqb_curinodes;
                        if (dquot->dq_curinodes < dquot->dq_isoftlimit)
                                dquot->dq_flags &= ~DQ_INODES;
                        if (dquot->dq_bsoftlimit &&
                            dquot->dq_curblocks < dquot->dq_bsoftlimit &&
                            dq_dqblk.dqb_curblocks >= dquot->dq_bsoftlimit)
                                dquot->dq_btime = CURRENT_TIME + dquot->dq_sb->s_dquot.block_expire[type];
                        dquot->dq_curblocks = dq_dqblk.dqb_curblocks;
                        if (dquot->dq_curblocks < dquot->dq_bsoftlimit)
                                dquot->dq_flags &= ~DQ_BLKS;
                }

                if (id == 0) {
                        dquot->dq_sb->s_dquot.block_expire[type] = dquot->dq_btime = dq_dqblk.dqb_btime;
                        dquot->dq_sb->s_dquot.inode_expire[type] = dquot->dq_itime = dq_dqblk.dqb_itime;
                }

                if (dq_dqblk.dqb_bhardlimit == 0 && dq_dqblk.dqb_bsoftlimit == 0 &&
                    dq_dqblk.dqb_ihardlimit == 0 && dq_dqblk.dqb_isoftlimit == 0)
                        dquot->dq_flags |= DQ_FAKE;
                else
                        dquot->dq_flags &= ~DQ_FAKE;

                dquot->dq_flags |= DQ_MOD;
                dqput(dquot);
        }
        return 0;
}

static int get_quota(struct super_block *sb, int id, short type, struct dqblk *dqblk)
{
        struct dquot *dquot;
        struct dqblk data;
        int error = -ESRCH;

        if (!sb || !sb_has_quota_enabled(sb, type))
                goto out;
        dquot = dqget(sb, id, type);
        if (dquot == NODQUOT)
                goto out;

        memcpy(&data, &dquot->dq_dqb, sizeof(struct dqblk));        /* We copy data to preserve them from changing */
        dqput(dquot);
        error = -EFAULT;
        if (dqblk && !copy_to_user(dqblk, &data, sizeof(struct dqblk)))
                error = 0;
out:
        return error;
}

static int get_stats(caddr_t addr)
{
        int error = -EFAULT;
        struct dqstats stats;

        dqstats.allocated_dquots = nr_dquots;
        dqstats.free_dquots = nr_free_dquots;

        /* make a copy, in case we page-fault in user space */
        memcpy(&stats, &dqstats, sizeof(struct dqstats));
        if (!copy_to_user(addr, &stats, sizeof(struct dqstats)))
                error = 0;
        return error;
}

static int quota_root_squash(struct super_block *sb, short type, int *addr)
{
        int new_value, error;

        if (!sb)
                return(-ENODEV);

        error = -EFAULT;
        if (!copy_from_user(&new_value, addr, sizeof(int))) {
                sb_dqopt(sb)->rsquash[type] = new_value;
                error = 0;
        }
        return error;
}

#if 0   /* We are not going to support filesystems without i_blocks... */
/*
 * This is a simple algorithm that calculates the size of a file in blocks.
 * This is only used on filesystems that do not have an i_blocks count.
 */
static u_long isize_to_blocks(loff_t isize, size_t blksize_bits)
{
        u_long blocks;
        u_long indirect;

        if (!blksize_bits)
                blksize_bits = BLOCK_SIZE_BITS;
        blocks = (isize >> blksize_bits) + ((isize & ~((1 << blksize_bits)-1)) ? 1 : 0);
        if (blocks > 10) {
                indirect = ((blocks - 11) >> 8) + 1; /* single indirect blocks */
                if (blocks > (10 + 256)) {
                        indirect += ((blocks - 267) >> 16) + 1; /* double indirect blocks */
                        if (blocks > (10 + 256 + (256 << 8)))
                                indirect++; /* triple indirect blocks */
                }
                blocks += indirect;
        }
        return blocks;
}
#endif

/*
 * Externally referenced functions through dquot_operations in inode.
 *
 * Note: this is a blocking operation.
 */
void dquot_initialize(struct inode *inode, short type)
{
        struct dquot *dquot[MAXQUOTAS];
        unsigned int id = 0;
        short cnt;

        if (IS_NOQUOTA(inode))
                return;
        /* Build list of quotas to initialize... We can block here */
        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                dquot[cnt] = NODQUOT;
                if (type != -1 && cnt != type)
                        continue;
                if (!sb_has_quota_enabled(inode->i_sb, cnt))
                        continue;
                if (inode->i_dquot[cnt] == NODQUOT) {
                        switch (cnt) {
                                case USRQUOTA:
                                        id = inode->i_uid;
                                        break;
                                case GRPQUOTA:
                                        id = inode->i_gid;
                                        break;
                        }
                        dquot[cnt] = dqget(inode->i_sb, id, cnt);
                }
        }
        /* NOBLOCK START: Here we shouldn't block */
        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                if (dquot[cnt] == NODQUOT || !sb_has_quota_enabled(inode->i_sb, cnt) || inode->i_dquot[cnt] != NODQUOT)
                        continue;
                inode->i_dquot[cnt] = dquot[cnt];
                dquot[cnt] = NODQUOT;
                inode->i_flags |= S_QUOTA;
        }
        /* NOBLOCK END */
        /* Put quotas which we didn't use */
        for (cnt = 0; cnt < MAXQUOTAS; cnt++)
                if (dquot[cnt] != NODQUOT)
                        dqput(dquot[cnt]);
}

/*
 * Release all quota for the specified inode.
 *
 * Note: this is a blocking operation.

 */
void dquot_drop(struct inode *inode)
{
        struct dquot *dquot;
        short cnt;

        inode->i_flags &= ~S_QUOTA;
        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                if (inode->i_dquot[cnt] == NODQUOT)
                        continue;
                dquot = inode->i_dquot[cnt];
                inode->i_dquot[cnt] = NODQUOT;
                dqput(dquot);
        }
}

/*
 * This operation can block, but only after everything is updated
 */
int dquot_alloc_block(struct inode *inode, unsigned long number, char warn)
{
        int cnt, ret = NO_QUOTA;
        struct dquot *dquot[MAXQUOTAS];
        char warntype[MAXQUOTAS];

        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                dquot[cnt] = NODQUOT;
                warntype[cnt] = NOWARN;
        }
        /* NOBLOCK Start */
        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                dquot[cnt] = dqduplicate(inode->i_dquot[cnt]);
                if (dquot[cnt] == NODQUOT)
                        continue;
                if (check_bdq(dquot[cnt], number, warn, warntype+cnt) == NO_QUOTA)
                        goto warn_put_all;
        }
        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                if (dquot[cnt] == NODQUOT)
                        continue;
                dquot_incr_blocks(dquot[cnt], number);
        }
        inode->i_blocks += number << (BLOCK_SIZE_BITS - 9);
        /* NOBLOCK End */
        ret = QUOTA_OK;
warn_put_all:
        flush_warnings(dquot, warntype);
        for (cnt = 0; cnt < MAXQUOTAS; cnt++)
                if (dquot[cnt] != NODQUOT)
                        dqput(dquot[cnt]);
        return ret;
}

/*
 * This operation can block, but only after everything is updated
 */
int dquot_alloc_inode(const struct inode *inode, unsigned long number)
{
        int cnt, ret = NO_QUOTA;
        struct dquot *dquot[MAXQUOTAS];
        char warntype[MAXQUOTAS];

        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                dquot[cnt] = NODQUOT;
                warntype[cnt] = NOWARN;
        }
        /* NOBLOCK Start */
        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                dquot[cnt] = dqduplicate(inode -> i_dquot[cnt]);
                if (dquot[cnt] == NODQUOT)
                        continue;
                if (check_idq(dquot[cnt], number, warntype+cnt) == NO_QUOTA)
                        goto warn_put_all;
        }

        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                if (dquot[cnt] == NODQUOT)
                        continue;
                dquot_incr_inodes(dquot[cnt], number);
        }
        /* NOBLOCK End */
        ret = QUOTA_OK;
warn_put_all:
        flush_warnings(dquot, warntype);
        for (cnt = 0; cnt < MAXQUOTAS; cnt++)
                if (dquot[cnt] != NODQUOT)
                        dqput(dquot[cnt]);
        return ret;
}

/*
 * This is a non-blocking operation.
 */
void dquot_free_block(struct inode *inode, unsigned long number)
{
        unsigned short cnt;
        struct dquot *dquot;

        /* NOBLOCK Start */
        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                dquot = dqduplicate(inode->i_dquot[cnt]);
                if (dquot == NODQUOT)
                        continue;
                dquot_decr_blocks(dquot, number);
                dqput(dquot);
        }
        inode->i_blocks -= number << (BLOCK_SIZE_BITS - 9);
        /* NOBLOCK End */
}

/*
 * This is a non-blocking operation.
 */
void dquot_free_inode(const struct inode *inode, unsigned long number)
{
        unsigned short cnt;
        struct dquot *dquot;

        /* NOBLOCK Start */
        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                dquot = dqduplicate(inode->i_dquot[cnt]);
                if (dquot == NODQUOT)
                        continue;
                dquot_decr_inodes(dquot, number);
                dqput(dquot);
        }
        /* NOBLOCK End */
}

/*
 * Transfer the number of inode and blocks from one diskquota to an other.
 *
 * This operation can block, but only after everything is updated
 */
int dquot_transfer(struct inode *inode, struct iattr *iattr)
{
        unsigned long blocks;
        struct dquot *transfer_from[MAXQUOTAS];
        struct dquot *transfer_to[MAXQUOTAS];
        int cnt, ret = NO_QUOTA, 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[MAXQUOTAS];

        /* Clear the arrays */
        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                transfer_to[cnt] = transfer_from[cnt] = NODQUOT;
                warntype[cnt] = NOWARN;
        }
        /* First build the transfer_to list - here we can block on reading of dquots... */
        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                if (!sb_has_quota_enabled(inode->i_sb, cnt))
                        continue;
                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;
                }
        }
        /* NOBLOCK START: From now on we shouldn't block */
        blocks = (inode->i_blocks >> 1);
        /* Build the transfer_from list and check the limits */
        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                /* The second test can fail when quotaoff is in progress... */
                if (transfer_to[cnt] == NODQUOT || !sb_has_quota_enabled(inode->i_sb, cnt))
                        continue;
                transfer_from[cnt] = dqduplicate(inode->i_dquot[cnt]);
                if (transfer_from[cnt] == NODQUOT)      /* Can happen on quotafiles (quota isn't initialized on them)... */
                        continue;
                if (check_idq(transfer_to[cnt], 1, warntype+cnt) == NO_QUOTA ||
                    check_bdq(transfer_to[cnt], blocks, 0, warntype+cnt) == NO_QUOTA)
                        goto warn_put_all;
        }

        /*
         * 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 non-existing quota-type.
                 */
                if (transfer_from[cnt] == NODQUOT || transfer_to[cnt] == NODQUOT)
                        continue;

                dquot_decr_inodes(transfer_from[cnt], 1);
                dquot_decr_blocks(transfer_from[cnt], blocks);

                dquot_incr_inodes(transfer_to[cnt], 1);
                dquot_incr_blocks(transfer_to[cnt], blocks);

                if (inode->i_dquot[cnt] == NODQUOT)
                        BUG();
                inode->i_dquot[cnt] = transfer_to[cnt];
                /*
                 * We've got to release transfer_from[] twice - once for dquot_transfer() and
                 * once for inode. We don't want to release transfer_to[] as it's now placed in inode
                 */
                transfer_to[cnt] = transfer_from[cnt];
        }
        /* NOBLOCK END. From now on we can block as we wish */
        ret = QUOTA_OK;
warn_put_all:
        flush_warnings(transfer_to, warntype);
        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                if (transfer_to[cnt] != NODQUOT)
                        dqput(transfer_to[cnt]);
                if (transfer_from[cnt] != NODQUOT)
                        dqput(transfer_from[cnt]);
        }
        return ret;
}

static int __init dquot_init(void)
{
        int i;

        for (i = 0; i < NR_DQHASH; i++)
                INIT_LIST_HEAD(dquot_hash + i);
        printk(KERN_NOTICE "VFS: Diskquotas version %s initialized\n", __DQUOT_VERSION__);
        return 0;
}
__initcall(dquot_init);

/*
 * Definitions of diskquota operations.
 */
struct dquot_operations dquot_operations = {
        dquot_initialize,               /* mandatory */
        dquot_drop,                     /* mandatory */
        dquot_alloc_block,
        dquot_alloc_inode,
        dquot_free_block,
        dquot_free_inode,
        dquot_transfer
};

static inline void set_enable_flags(struct quota_mount_options *dqopt, short type)
{
        switch (type) {
                case USRQUOTA:
                        dqopt->flags |= DQUOT_USR_ENABLED;
                        break;
                case GRPQUOTA:
                        dqopt->flags |= DQUOT_GRP_ENABLED;
                        break;
        }
}

static inline void reset_enable_flags(struct quota_mount_options *dqopt, short type)
{
        switch (type) {
                case USRQUOTA:
                        dqopt->flags &= ~DQUOT_USR_ENABLED;
                        break;
                case GRPQUOTA:
                        dqopt->flags &= ~DQUOT_GRP_ENABLED;
                        break;
        }
}

/* Function in inode.c - remove pointers to dquots in icache */
extern void remove_dquot_ref(struct super_block *, short);

/*
 * Turn quota off on a device. type == -1 ==> quotaoff for all types (umount)
 */
int quota_off(struct super_block *sb, short type)
{
        struct file *filp;
        short cnt;
        struct quota_mount_options *dqopt = sb_dqopt(sb);

        lock_kernel();
        if (!sb)
                goto out;

        /* We need to serialize quota_off() for device */
        down(&dqopt->dqoff_sem);
        for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
                if (type != -1 && cnt != type)
                        continue;
                if (!is_enabled(dqopt, cnt))
                        continue;
                reset_enable_flags(dqopt, cnt);

                /* Note: these are blocking operations */
                remove_dquot_ref(sb, cnt);
                invalidate_dquots(sb, cnt);

                filp = dqopt->files[cnt];
                dqopt->files[cnt] = (struct file *)NULL;
                dqopt->inode_expire[cnt] = 0;
                dqopt->block_expire[cnt] = 0;
                fput(filp);
        }       
        up(&dqopt->dqoff_sem);
out:
        unlock_kernel();
        return 0;
}

static inline int check_quotafile_size(loff_t size)
{
        ulong blocks = size >> BLOCK_SIZE_BITS;
        size_t off = size & (BLOCK_SIZE - 1);

        return !(((blocks % sizeof(struct dqblk)) * BLOCK_SIZE + off % sizeof(struct dqblk)) % sizeof(struct dqblk));
}

static int quota_on(struct super_block *sb, short type, char *path)
{
        struct file *f;
        struct inode *inode;
        struct dquot *dquot;
        struct quota_mount_options *dqopt = sb_dqopt(sb);
        char *tmp;
        int error;

        if (is_enabled(dqopt, type))
                return -EBUSY;

        down(&dqopt->dqoff_sem);
        tmp = getname(path);
        error = PTR_ERR(tmp);
        if (IS_ERR(tmp))
                goto out_lock;

        f = filp_open(tmp, O_RDWR, 0600);
        putname(tmp);

        error = PTR_ERR(f);
        if (IS_ERR(f))
                goto out_lock;
        error = -EIO;
        if (!f->f_op || !f->f_op->read || !f->f_op->write)
                goto out_f;
        inode = f->f_dentry->d_inode;
        error = -EACCES;
        if (!S_ISREG(inode->i_mode))
                goto out_f;
        error = -EINVAL;
        if (inode->i_size == 0 || !check_quotafile_size(inode->i_size))
                goto out_f;
        /* We don't want quota on quota files */
        dquot_drop(inode);
        inode->i_flags |= S_NOQUOTA;

        dqopt->files[type] = f;
        sb->dq_op = &dquot_operations;
        set_enable_flags(dqopt, type);

        dquot = dqget(sb, 0, type);
        dqopt->inode_expire[type] = (dquot != NODQUOT) ? dquot->dq_itime : MAX_IQ_TIME;
        dqopt->block_expire[type] = (dquot != NODQUOT) ? dquot->dq_btime : MAX_DQ_TIME;
        dqput(dquot);

        add_dquot_ref(sb, type);

        up(&dqopt->dqoff_sem);
        return 0;

out_f:
        filp_close(f, NULL);
out_lock:
        up(&dqopt->dqoff_sem);

        return error; 
}

/*
 * This is the system call interface. This communicates with
 * the user-level programs. Currently this only supports diskquota
 * calls. Maybe we need to add the process quotas etc. in the future,
 * but we probably should use rlimits for that.
 */
asmlinkage long sys_quotactl(int cmd, const char *special, int id, caddr_t addr)
{
        int cmds = 0, type = 0, flags = 0;
        kdev_t dev;
        struct super_block *sb = NULL;
        int ret = -EINVAL;

        lock_kernel();
        cmds = cmd >> SUBCMDSHIFT;
        type = cmd & SUBCMDMASK;

        if ((u_int) type >= MAXQUOTAS)
                goto out;
        if (id & ~0xFFFF)
                goto out;

        ret = -EPERM;
        switch (cmds) {
                case Q_SYNC:
                case Q_GETSTATS:
                        break;
                case Q_GETQUOTA:
                        if (((type == USRQUOTA && current->euid != id) ||
                             (type == GRPQUOTA && !in_egroup_p(id))) &&
                            !capable(CAP_SYS_ADMIN))
                                goto out;
                        break;
                default:
                        if (!capable(CAP_SYS_ADMIN))
                                goto out;
        }

        ret = -EINVAL;
        dev = NODEV;
        if (special != NULL || (cmds != Q_SYNC && cmds != Q_GETSTATS)) {
                mode_t mode;
                struct nameidata nd;

                ret = user_path_walk(special, &nd);
                if (ret)
                        goto out;

                dev = nd.dentry->d_inode->i_rdev;
                mode = nd.dentry->d_inode->i_mode;
                path_release(&nd);

                ret = -ENOTBLK;
                if (!S_ISBLK(mode))
                        goto out;
                ret = -ENODEV;
                sb = get_super(dev);
                if (!sb)
                        goto out;
        }

        ret = -EINVAL;
        switch (cmds) {
                case Q_QUOTAON:
                        ret = quota_on(sb, type, (char *) addr);
                        goto out;
                case Q_QUOTAOFF:
                        ret = quota_off(sb, type);
                        goto out;
                case Q_GETQUOTA:
                        ret = get_quota(sb, id, type, (struct dqblk *) addr);
                        goto out;
                case Q_SETQUOTA:
                        flags |= SET_QUOTA;
                        break;
                case Q_SETUSE:
                        flags |= SET_USE;
                        break;
                case Q_SETQLIM:
                        flags |= SET_QLIMIT;
                        break;
                case Q_SYNC:
                        ret = sync_dquots(dev, type);
                        goto out;
                case Q_GETSTATS:
                        ret = get_stats(addr);
                        goto out;
                case Q_RSQUASH:
                        ret = quota_root_squash(sb, type, (int *) addr);
                        goto out;
                default:
                        goto out;
        }

        ret = -NODEV;
        if (sb && sb_has_quota_enabled(sb, type))
                ret = set_dqblk(sb, id, type, flags, (struct dqblk *) addr);
out:
        if (sb)
                drop_super(sb);
        unlock_kernel();
        return ret;
}