[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / quota / quota.c

/*
 * Quota code necessary even when VFS quota support is not compiled
 * into the kernel.  The interesting stuff is over in dquot.c, here
 * we have symbols for initial quotactl(2) handling, the sysctl(2)
 * variables, etc - things needed even when quota support disabled.
 */

#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/slab.h>
#include <asm/current.h>
#include <asm/uaccess.h>
#include <linux/kernel.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/buffer_head.h>
#include <linux/capability.h>
#include <linux/quotaops.h>
#include <linux/types.h>
#include <linux/writeback.h>

static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
				     qid_t id)
{
	switch (cmd) {
	/* these commands do not require any special privilegues */
	case Q_GETFMT:
	case Q_SYNC:
	case Q_GETINFO:
	case Q_XGETQSTAT:
	case Q_XQUOTASYNC:
		break;
	/* allow to query information for dquots we "own" */
	case Q_GETQUOTA:
	case Q_XGETQUOTA:
		if ((type == USRQUOTA && current_euid() == id) ||
		    (type == GRPQUOTA && in_egroup_p(id)))
			break;
		/*FALLTHROUGH*/
	default:
		if (!capable(CAP_SYS_ADMIN))
			return -EPERM;
	}

	return security_quotactl(cmd, type, id, sb);
}

static int quota_sync_all(int type)
{
	struct super_block *sb;
	int ret;

	if (type >= MAXQUOTAS)
		return -EINVAL;
	ret = security_quotactl(Q_SYNC, type, 0, NULL);
	if (ret)
		return ret;

	spin_lock(&sb_lock);
restart:
	list_for_each_entry(sb, &super_blocks, s_list) {
		if (!sb->s_qcop || !sb->s_qcop->quota_sync)
			continue;

		sb->s_count++;
		spin_unlock(&sb_lock);
		down_read(&sb->s_umount);
		if (sb->s_root)
			sb->s_qcop->quota_sync(sb, type, 1);
		up_read(&sb->s_umount);
		spin_lock(&sb_lock);
		if (__put_super_and_need_restart(sb))
			goto restart;
	}
	spin_unlock(&sb_lock);

	return 0;
}

static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
		         void __user *addr)
{
	char *pathname;
	int ret = -ENOSYS;

	pathname = getname(addr);
	if (IS_ERR(pathname))
		return PTR_ERR(pathname);
	if (sb->s_qcop->quota_on)
		ret = sb->s_qcop->quota_on(sb, type, id, pathname, 0);
	putname(pathname);
	return ret;
}

static int quota_getfmt(struct super_block *sb, int type, void __user *addr)
{
	__u32 fmt;

	down_read(&sb_dqopt(sb)->dqptr_sem);
	if (!sb_has_quota_active(sb, type)) {
		up_read(&sb_dqopt(sb)->dqptr_sem);
		return -ESRCH;
	}
	fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
	up_read(&sb_dqopt(sb)->dqptr_sem);
	if (copy_to_user(addr, &fmt, sizeof(fmt)))
		return -EFAULT;
	return 0;
}

static int quota_getinfo(struct super_block *sb, int type, void __user *addr)
{
	struct if_dqinfo info;
	int ret;

	if (!sb_has_quota_active(sb, type))
		return -ESRCH;
	if (!sb->s_qcop->get_info)
		return -ENOSYS;
	ret = sb->s_qcop->get_info(sb, type, &info);
	if (!ret && copy_to_user(addr, &info, sizeof(info)))
		return -EFAULT;
	return ret;
}

static int quota_setinfo(struct super_block *sb, int type, void __user *addr)
{
	struct if_dqinfo info;

	if (copy_from_user(&info, addr, sizeof(info)))
		return -EFAULT;
	if (!sb_has_quota_active(sb, type))
		return -ESRCH;
	if (!sb->s_qcop->set_info)
		return -ENOSYS;
	return sb->s_qcop->set_info(sb, type, &info);
}

static void copy_to_if_dqblk(struct if_dqblk *dst, struct fs_disk_quota *src)
{
	dst->dqb_bhardlimit = src->d_blk_hardlimit;
	dst->dqb_bsoftlimit = src->d_blk_softlimit;
	dst->dqb_curspace = src->d_bcount;
	dst->dqb_ihardlimit = src->d_ino_hardlimit;
	dst->dqb_isoftlimit = src->d_ino_softlimit;
	dst->dqb_curinodes = src->d_icount;
	dst->dqb_btime = src->d_btimer;
	dst->dqb_itime = src->d_itimer;
	dst->dqb_valid = QIF_ALL;
}

static int quota_getquota(struct super_block *sb, int type, qid_t id,
			  void __user *addr)
{
	struct fs_disk_quota fdq;
	struct if_dqblk idq;
	int ret;

	if (!sb->s_qcop->get_dqblk)
		return -ENOSYS;
	ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
	if (ret)
		return ret;
	copy_to_if_dqblk(&idq, &fdq);
	if (copy_to_user(addr, &idq, sizeof(idq)))
		return -EFAULT;
	return 0;
}

static int quota_setquota(struct super_block *sb, int type, qid_t id,
			  void __user *addr)
{
	struct if_dqblk idq;

	if (copy_from_user(&idq, addr, sizeof(idq)))
		return -EFAULT;
	if (!sb_has_quota_active(sb, type))
		return -ESRCH;
	if (!sb->s_qcop->set_dqblk)
		return -ENOSYS;
	return sb->s_qcop->set_dqblk(sb, type, id, &idq);
}

static int quota_setxstate(struct super_block *sb, int cmd, void __user *addr)
{
	__u32 flags;

	if (copy_from_user(&flags, addr, sizeof(flags)))
		return -EFAULT;
	if (!sb->s_qcop->set_xstate)
		return -ENOSYS;
	return sb->s_qcop->set_xstate(sb, flags, cmd);
}

static int quota_getxstate(struct super_block *sb, void __user *addr)
{
	struct fs_quota_stat fqs;
	int ret;

	if (!sb->s_qcop->get_xstate)
		return -ENOSYS;
	ret = sb->s_qcop->get_xstate(sb, &fqs);
	if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
		return -EFAULT;
	return ret;
}

static int quota_setxquota(struct super_block *sb, int type, qid_t id,
			   void __user *addr)
{
	struct fs_disk_quota fdq;

	if (copy_from_user(&fdq, addr, sizeof(fdq)))
		return -EFAULT;
	if (!sb->s_qcop->set_xquota)
		return -ENOSYS;
	return sb->s_qcop->set_xquota(sb, type, id, &fdq);
}

static int quota_getxquota(struct super_block *sb, int type, qid_t id,
			   void __user *addr)
{
	struct fs_disk_quota fdq;
	int ret;

	if (!sb->s_qcop->get_dqblk)
		return -ENOSYS;
	ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
	if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
		return -EFAULT;
	return ret;
}

/* Copy parameters and call proper function */
static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
		       void __user *addr)
{
	int ret;

	if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
		return -EINVAL;
	if (!sb->s_qcop)
		return -ENOSYS;

	ret = check_quotactl_permission(sb, type, cmd, id);
	if (ret < 0)
		return ret;

	switch (cmd) {
	case Q_QUOTAON:
		return quota_quotaon(sb, type, cmd, id, addr);
	case Q_QUOTAOFF:
		if (!sb->s_qcop->quota_off)
			return -ENOSYS;
		return sb->s_qcop->quota_off(sb, type, 0);
	case Q_GETFMT:
		return quota_getfmt(sb, type, addr);
	case Q_GETINFO:
		return quota_getinfo(sb, type, addr);
	case Q_SETINFO:
		return quota_setinfo(sb, type, addr);
	case Q_GETQUOTA:
		return quota_getquota(sb, type, id, addr);
	case Q_SETQUOTA:
		return quota_setquota(sb, type, id, addr);
	case Q_SYNC:
		if (!sb->s_qcop->quota_sync)
			return -ENOSYS;
		return sb->s_qcop->quota_sync(sb, type, 1);
	case Q_XQUOTAON:
	case Q_XQUOTAOFF:
	case Q_XQUOTARM:
		return quota_setxstate(sb, cmd, addr);
	case Q_XGETQSTAT:
		return quota_getxstate(sb, addr);
	case Q_XSETQLIM:
		return quota_setxquota(sb, type, id, addr);
	case Q_XGETQUOTA:
		return quota_getxquota(sb, type, id, addr);
	case Q_XQUOTASYNC:
		/* caller already holds s_umount */
		if (sb->s_flags & MS_RDONLY)
			return -EROFS;
		writeback_inodes_sb(sb);
		return 0;
	default:
		return -EINVAL;
	}
}

/*
 * look up a superblock on which quota ops will be performed
 * - use the name of a block device to find the superblock thereon
 */
static struct super_block *quotactl_block(const char __user *special)
{
#ifdef CONFIG_BLOCK
	struct block_device *bdev;
	struct super_block *sb;
	char *tmp = getname(special);

	if (IS_ERR(tmp))
		return ERR_CAST(tmp);
	bdev = lookup_bdev(tmp);
	putname(tmp);
	if (IS_ERR(bdev))
		return ERR_CAST(bdev);
	sb = get_super(bdev);
	bdput(bdev);
	if (!sb)
		return ERR_PTR(-ENODEV);

	return sb;
#else
	return ERR_PTR(-ENODEV);
#endif
}

/*
 * 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.
 */
SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
		qid_t, id, void __user *, addr)
{
	uint cmds, type;
	struct super_block *sb = NULL;
	int ret;

	cmds = cmd >> SUBCMDSHIFT;
	type = cmd & SUBCMDMASK;

	/*
	 * As a special case Q_SYNC can be called without a specific device.
	 * It will iterate all superblocks that have quota enabled and call
	 * the sync action on each of them.
	 */
	if (!special) {
		if (cmds == Q_SYNC)
			return quota_sync_all(type);
		return -ENODEV;
	}

	sb = quotactl_block(special);
	if (IS_ERR(sb))
		return PTR_ERR(sb);

	ret = do_quotactl(sb, type, cmds, id, addr);

	drop_super(sb);
	return ret;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Quota code necessary even when VFS quota support is not compiled
	3	* into the kernel. The interesting stuff is over in dquot.c, here
	4	* we have symbols for initial quotactl(2) handling, the sysctl(2)
	5	* variables, etc - things needed even when quota support disabled.
	6	*/
	7
	8	#include <linux/fs.h>
	9	#include <linux/namei.h>
	10	#include <linux/slab.h>
	11	#include <asm/current.h>
	12	#include <asm/uaccess.h>
	13	#include <linux/kernel.h>
1da177e4 LT	14	#include <linux/security.h>
	15	#include <linux/syscalls.h>
	16	#include <linux/buffer_head.h>
16f7e0fe	17	#include <linux/capability.h>
be586bab	18	#include <linux/quotaops.h>
b716395e	19	#include <linux/types.h>
8c4e4acd	20	#include <linux/writeback.h>
1da177e4	21
c988afb5 CH	22	static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
c988afb5 CH	23	qid_t id)
1da177e4	24	{
c988afb5 CH	25	switch (cmd) {
	26	/* these commands do not require any special privilegues */
	27	case Q_GETFMT:
	28	case Q_SYNC:
	29	case Q_GETINFO:
	30	case Q_XGETQSTAT:
	31	case Q_XQUOTASYNC:
	32	break;
	33	/* allow to query information for dquots we "own" */
	34	case Q_GETQUOTA:
	35	case Q_XGETQUOTA:
	36	if ((type == USRQUOTA && current_euid() == id) \|\|
	37	(type == GRPQUOTA && in_egroup_p(id)))
	38	break;
	39	/FALLTHROUGH/
	40	default:
1da177e4 LT	41	if (!capable(CAP_SYS_ADMIN))
	42	return -EPERM;
	43	}
	44
c988afb5	45	return security_quotactl(cmd, type, id, sb);
1da177e4 LT	46	}
1da177e4 LT	47
6ae09575	48	static int quota_sync_all(int type)
1da177e4	49	{
850b201b	50	struct super_block *sb;
6ae09575 CH	51	int ret;
	52
	53	if (type >= MAXQUOTAS)
	54	return -EINVAL;
	55	ret = security_quotactl(Q_SYNC, type, 0, NULL);
	56	if (ret)
	57	return ret;
618f0636	58
618f0636 KK	59	spin_lock(&sb_lock);
	60	restart:
	61	list_for_each_entry(sb, &super_blocks, s_list) {
5fb324ad CH	62	if (!sb->s_qcop \|\| !sb->s_qcop->quota_sync)
	63	continue;
	64
618f0636 KK	65	sb->s_count++;
	66	spin_unlock(&sb_lock);
	67	down_read(&sb->s_umount);
850b201b	68	if (sb->s_root)
5fb324ad	69	sb->s_qcop->quota_sync(sb, type, 1);
618f0636 KK	70	up_read(&sb->s_umount);
	71	spin_lock(&sb_lock);
	72	if (__put_super_and_need_restart(sb))
	73	goto restart;
1da177e4	74	}
618f0636	75	spin_unlock(&sb_lock);
6ae09575 CH	76
6ae09575 CH	77	return 0;
1da177e4 LT	78	}
1da177e4 LT	79
c411e5f6 CH	80	static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
c411e5f6 CH	81	void __user *addr)
1da177e4	82	{
c411e5f6	83	char *pathname;
f450d4fe	84	int ret = -ENOSYS;
1da177e4	85
c411e5f6 CH	86	pathname = getname(addr);
	87	if (IS_ERR(pathname))
	88	return PTR_ERR(pathname);
f450d4fe CH	89	if (sb->s_qcop->quota_on)
f450d4fe CH	90	ret = sb->s_qcop->quota_on(sb, type, id, pathname, 0);
c411e5f6 CH	91	putname(pathname);
	92	return ret;
	93	}
1da177e4	94
c411e5f6 CH	95	static int quota_getfmt(struct super_block sb, int type, void __user addr)
	96	{
	97	__u32 fmt;
1da177e4	98
c411e5f6 CH	99	down_read(&sb_dqopt(sb)->dqptr_sem);
	100	if (!sb_has_quota_active(sb, type)) {
	101	up_read(&sb_dqopt(sb)->dqptr_sem);
	102	return -ESRCH;
	103	}
	104	fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
	105	up_read(&sb_dqopt(sb)->dqptr_sem);
	106	if (copy_to_user(addr, &fmt, sizeof(fmt)))
	107	return -EFAULT;
	108	return 0;
	109	}
1da177e4	110
c411e5f6 CH	111	static int quota_getinfo(struct super_block sb, int type, void __user addr)
	112	{
	113	struct if_dqinfo info;
	114	int ret;
1da177e4	115
f450d4fe CH	116	if (!sb_has_quota_active(sb, type))
	117	return -ESRCH;
	118	if (!sb->s_qcop->get_info)
	119	return -ENOSYS;
c411e5f6 CH	120	ret = sb->s_qcop->get_info(sb, type, &info);
	121	if (!ret && copy_to_user(addr, &info, sizeof(info)))
	122	return -EFAULT;
	123	return ret;
	124	}
1da177e4	125
c411e5f6 CH	126	static int quota_setinfo(struct super_block sb, int type, void __user addr)
	127	{
	128	struct if_dqinfo info;
1da177e4	129
c411e5f6 CH	130	if (copy_from_user(&info, addr, sizeof(info)))
c411e5f6 CH	131	return -EFAULT;
f450d4fe CH	132	if (!sb_has_quota_active(sb, type))
	133	return -ESRCH;
	134	if (!sb->s_qcop->set_info)
	135	return -ENOSYS;
c411e5f6 CH	136	return sb->s_qcop->set_info(sb, type, &info);
	137	}
	138
b9b2dd36 CH	139	static void copy_to_if_dqblk(struct if_dqblk dst, struct fs_disk_quota src)
	140	{
	141	dst->dqb_bhardlimit = src->d_blk_hardlimit;
	142	dst->dqb_bsoftlimit = src->d_blk_softlimit;
	143	dst->dqb_curspace = src->d_bcount;
	144	dst->dqb_ihardlimit = src->d_ino_hardlimit;
	145	dst->dqb_isoftlimit = src->d_ino_softlimit;
	146	dst->dqb_curinodes = src->d_icount;
	147	dst->dqb_btime = src->d_btimer;
	148	dst->dqb_itime = src->d_itimer;
	149	dst->dqb_valid = QIF_ALL;
	150	}
	151
c411e5f6 CH	152	static int quota_getquota(struct super_block *sb, int type, qid_t id,
	153	void __user *addr)
	154	{
b9b2dd36	155	struct fs_disk_quota fdq;
c411e5f6 CH	156	struct if_dqblk idq;
	157	int ret;
	158
f450d4fe CH	159	if (!sb->s_qcop->get_dqblk)
f450d4fe CH	160	return -ENOSYS;
b9b2dd36	161	ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
c411e5f6 CH	162	if (ret)
c411e5f6 CH	163	return ret;
b9b2dd36	164	copy_to_if_dqblk(&idq, &fdq);
c411e5f6 CH	165	if (copy_to_user(addr, &idq, sizeof(idq)))
	166	return -EFAULT;
	167	return 0;
	168	}
	169
	170	static int quota_setquota(struct super_block *sb, int type, qid_t id,
	171	void __user *addr)
	172	{
	173	struct if_dqblk idq;
	174
	175	if (copy_from_user(&idq, addr, sizeof(idq)))
	176	return -EFAULT;
f450d4fe CH	177	if (!sb_has_quota_active(sb, type))
	178	return -ESRCH;
	179	if (!sb->s_qcop->set_dqblk)
	180	return -ENOSYS;
c411e5f6 CH	181	return sb->s_qcop->set_dqblk(sb, type, id, &idq);
	182	}
	183
	184	static int quota_setxstate(struct super_block sb, int cmd, void __user addr)
	185	{
	186	__u32 flags;
	187
	188	if (copy_from_user(&flags, addr, sizeof(flags)))
	189	return -EFAULT;
f450d4fe CH	190	if (!sb->s_qcop->set_xstate)
f450d4fe CH	191	return -ENOSYS;
c411e5f6 CH	192	return sb->s_qcop->set_xstate(sb, flags, cmd);
	193	}
	194
	195	static int quota_getxstate(struct super_block sb, void __user addr)
	196	{
	197	struct fs_quota_stat fqs;
	198	int ret;
f450d4fe CH	199
	200	if (!sb->s_qcop->get_xstate)
	201	return -ENOSYS;
c411e5f6 CH	202	ret = sb->s_qcop->get_xstate(sb, &fqs);
	203	if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
	204	return -EFAULT;
	205	return ret;
	206	}
1da177e4	207
c411e5f6 CH	208	static int quota_setxquota(struct super_block *sb, int type, qid_t id,
	209	void __user *addr)
	210	{
	211	struct fs_disk_quota fdq;
	212
	213	if (copy_from_user(&fdq, addr, sizeof(fdq)))
	214	return -EFAULT;
f450d4fe CH	215	if (!sb->s_qcop->set_xquota)
f450d4fe CH	216	return -ENOSYS;
c411e5f6 CH	217	return sb->s_qcop->set_xquota(sb, type, id, &fdq);
	218	}
	219
	220	static int quota_getxquota(struct super_block *sb, int type, qid_t id,
	221	void __user *addr)
	222	{
	223	struct fs_disk_quota fdq;
	224	int ret;
	225
b9b2dd36	226	if (!sb->s_qcop->get_dqblk)
f450d4fe	227	return -ENOSYS;
b9b2dd36	228	ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
c411e5f6 CH	229	if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
	230	return -EFAULT;
	231	return ret;
	232	}
	233
	234	/* Copy parameters and call proper function */
	235	static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
	236	void __user *addr)
	237	{
c988afb5 CH	238	int ret;
	239
	240	if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
	241	return -EINVAL;
	242	if (!sb->s_qcop)
	243	return -ENOSYS;
	244
	245	ret = check_quotactl_permission(sb, type, cmd, id);
	246	if (ret < 0)
	247	return ret;
	248
c411e5f6 CH	249	switch (cmd) {
	250	case Q_QUOTAON:
	251	return quota_quotaon(sb, type, cmd, id, addr);
	252	case Q_QUOTAOFF:
f450d4fe CH	253	if (!sb->s_qcop->quota_off)
f450d4fe CH	254	return -ENOSYS;
c411e5f6 CH	255	return sb->s_qcop->quota_off(sb, type, 0);
	256	case Q_GETFMT:
	257	return quota_getfmt(sb, type, addr);
	258	case Q_GETINFO:
	259	return quota_getinfo(sb, type, addr);
	260	case Q_SETINFO:
	261	return quota_setinfo(sb, type, addr);
	262	case Q_GETQUOTA:
	263	return quota_getquota(sb, type, id, addr);
	264	case Q_SETQUOTA:
	265	return quota_setquota(sb, type, id, addr);
	266	case Q_SYNC:
6ae09575 CH	267	if (!sb->s_qcop->quota_sync)
6ae09575 CH	268	return -ENOSYS;
5fb324ad	269	return sb->s_qcop->quota_sync(sb, type, 1);
c411e5f6 CH	270	case Q_XQUOTAON:
	271	case Q_XQUOTAOFF:
	272	case Q_XQUOTARM:
	273	return quota_setxstate(sb, cmd, addr);
	274	case Q_XGETQSTAT:
	275	return quota_getxstate(sb, addr);
	276	case Q_XSETQLIM:
	277	return quota_setxquota(sb, type, id, addr);
	278	case Q_XGETQUOTA:
	279	return quota_getxquota(sb, type, id, addr);
	280	case Q_XQUOTASYNC:
8c4e4acd CH	281	/* caller already holds s_umount */
	282	if (sb->s_flags & MS_RDONLY)
	283	return -EROFS;
	284	writeback_inodes_sb(sb);
	285	return 0;
c411e5f6	286	default:
f450d4fe	287	return -EINVAL;
1da177e4	288	}
1da177e4 LT	289	}
1da177e4 LT	290
9361401e DH	291	/*
	292	* look up a superblock on which quota ops will be performed
	293	* - use the name of a block device to find the superblock thereon
	294	*/
7a2435d8	295	static struct super_block quotactl_block(const char __user special)
9361401e DH	296	{
	297	#ifdef CONFIG_BLOCK
	298	struct block_device *bdev;
	299	struct super_block *sb;
	300	char *tmp = getname(special);
	301
	302	if (IS_ERR(tmp))
e231c2ee	303	return ERR_CAST(tmp);
9361401e DH	304	bdev = lookup_bdev(tmp);
	305	putname(tmp);
	306	if (IS_ERR(bdev))
e231c2ee	307	return ERR_CAST(bdev);
9361401e DH	308	sb = get_super(bdev);
	309	bdput(bdev);
	310	if (!sb)
	311	return ERR_PTR(-ENODEV);
	312
	313	return sb;
	314	#else
	315	return ERR_PTR(-ENODEV);
	316	#endif
	317	}
	318
1da177e4 LT	319	/*
	320	* This is the system call interface. This communicates with
	321	* the user-level programs. Currently this only supports diskquota
	322	* calls. Maybe we need to add the process quotas etc. in the future,
	323	* but we probably should use rlimits for that.
	324	*/
3cdad428 HC	325	SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
3cdad428 HC	326	qid_t, id, void __user *, addr)
1da177e4 LT	327	{
	328	uint cmds, type;
	329	struct super_block *sb = NULL;
1da177e4 LT	330	int ret;
	331
	332	cmds = cmd >> SUBCMDSHIFT;
	333	type = cmd & SUBCMDMASK;
	334
6ae09575 CH	335	/*
	336	* As a special case Q_SYNC can be called without a specific device.
	337	* It will iterate all superblocks that have quota enabled and call
	338	* the sync action on each of them.
	339	*/
	340	if (!special) {
	341	if (cmds == Q_SYNC)
	342	return quota_sync_all(type);
	343	return -ENODEV;
1da177e4 LT	344	}
1da177e4 LT	345
6ae09575 CH	346	sb = quotactl_block(special);
	347	if (IS_ERR(sb))
	348	return PTR_ERR(sb);
	349
c988afb5	350	ret = do_quotactl(sb, type, cmds, id, addr);
1da177e4	351
6ae09575	352	drop_super(sb);
1da177e4 LT	353	return ret;
1da177e4 LT	354	}