[linux.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 void quota_sync_one(struct super_block *sb, void *arg)
{
	if (sb->s_qcop && sb->s_qcop->quota_sync)
		sb->s_qcop->quota_sync(sb, *(int *)arg, 1);
}

static int quota_sync_all(int type)
{
	int ret;

	if (type >= MAXQUOTAS)
		return -EINVAL;
	ret = security_quotactl(Q_SYNC, type, 0, NULL);
	if (!ret)
		iterate_supers(quota_sync_one, &type);
	return ret;
}

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

	dst->d_fieldmask = 0;
	if (src->dqb_valid & QIF_BLIMITS)
		dst->d_fieldmask |= FS_DQ_BSOFT | FS_DQ_BHARD;
	if (src->dqb_valid & QIF_SPACE)
		dst->d_fieldmask |= FS_DQ_BCOUNT;
	if (src->dqb_valid & QIF_ILIMITS)
		dst->d_fieldmask |= FS_DQ_ISOFT | FS_DQ_IHARD;
	if (src->dqb_valid & QIF_INODES)
		dst->d_fieldmask |= FS_DQ_ICOUNT;
	if (src->dqb_valid & QIF_BTIME)
		dst->d_fieldmask |= FS_DQ_BTIMER;
	if (src->dqb_valid & QIF_ITIME)
		dst->d_fieldmask |= FS_DQ_ITIMER;
}

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

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

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_dqblk)
		return -ENOSYS;
	return sb->s_qcop->set_dqblk(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
01a05b33 AV	48	static void quota_sync_one(struct super_block sb, void arg)
	49	{
	50	if (sb->s_qcop && sb->s_qcop->quota_sync)
	51	sb->s_qcop->quota_sync(sb, (int )arg, 1);
	52	}
	53
6ae09575	54	static int quota_sync_all(int type)
1da177e4	55	{
6ae09575 CH	56	int ret;
	57
	58	if (type >= MAXQUOTAS)
	59	return -EINVAL;
	60	ret = security_quotactl(Q_SYNC, type, 0, NULL);
01a05b33 AV	61	if (!ret)
	62	iterate_supers(quota_sync_one, &type);
	63	return ret;
1da177e4 LT	64	}
1da177e4 LT	65
c411e5f6 CH	66	static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
c411e5f6 CH	67	void __user *addr)
1da177e4	68	{
c411e5f6	69	char *pathname;
f450d4fe	70	int ret = -ENOSYS;
1da177e4	71
c411e5f6 CH	72	pathname = getname(addr);
	73	if (IS_ERR(pathname))
	74	return PTR_ERR(pathname);
f450d4fe CH	75	if (sb->s_qcop->quota_on)
f450d4fe CH	76	ret = sb->s_qcop->quota_on(sb, type, id, pathname, 0);
c411e5f6 CH	77	putname(pathname);
	78	return ret;
	79	}
1da177e4	80
c411e5f6 CH	81	static int quota_getfmt(struct super_block sb, int type, void __user addr)
	82	{
	83	__u32 fmt;
1da177e4	84
c411e5f6 CH	85	down_read(&sb_dqopt(sb)->dqptr_sem);
	86	if (!sb_has_quota_active(sb, type)) {
	87	up_read(&sb_dqopt(sb)->dqptr_sem);
	88	return -ESRCH;
	89	}
	90	fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
	91	up_read(&sb_dqopt(sb)->dqptr_sem);
	92	if (copy_to_user(addr, &fmt, sizeof(fmt)))
	93	return -EFAULT;
	94	return 0;
	95	}
1da177e4	96
c411e5f6 CH	97	static int quota_getinfo(struct super_block sb, int type, void __user addr)
	98	{
	99	struct if_dqinfo info;
	100	int ret;
1da177e4	101
f450d4fe CH	102	if (!sb->s_qcop->get_info)
f450d4fe CH	103	return -ENOSYS;
c411e5f6 CH	104	ret = sb->s_qcop->get_info(sb, type, &info);
	105	if (!ret && copy_to_user(addr, &info, sizeof(info)))
	106	return -EFAULT;
	107	return ret;
	108	}
1da177e4	109
c411e5f6 CH	110	static int quota_setinfo(struct super_block sb, int type, void __user addr)
	111	{
	112	struct if_dqinfo info;
1da177e4	113
c411e5f6 CH	114	if (copy_from_user(&info, addr, sizeof(info)))
c411e5f6 CH	115	return -EFAULT;
f450d4fe CH	116	if (!sb->s_qcop->set_info)
f450d4fe CH	117	return -ENOSYS;
c411e5f6 CH	118	return sb->s_qcop->set_info(sb, type, &info);
	119	}
	120
b9b2dd36 CH	121	static void copy_to_if_dqblk(struct if_dqblk dst, struct fs_disk_quota src)
	122	{
	123	dst->dqb_bhardlimit = src->d_blk_hardlimit;
	124	dst->dqb_bsoftlimit = src->d_blk_softlimit;
	125	dst->dqb_curspace = src->d_bcount;
	126	dst->dqb_ihardlimit = src->d_ino_hardlimit;
	127	dst->dqb_isoftlimit = src->d_ino_softlimit;
	128	dst->dqb_curinodes = src->d_icount;
	129	dst->dqb_btime = src->d_btimer;
	130	dst->dqb_itime = src->d_itimer;
	131	dst->dqb_valid = QIF_ALL;
	132	}
	133
c411e5f6 CH	134	static int quota_getquota(struct super_block *sb, int type, qid_t id,
	135	void __user *addr)
	136	{
b9b2dd36	137	struct fs_disk_quota fdq;
c411e5f6 CH	138	struct if_dqblk idq;
	139	int ret;
	140
f450d4fe CH	141	if (!sb->s_qcop->get_dqblk)
f450d4fe CH	142	return -ENOSYS;
b9b2dd36	143	ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
c411e5f6 CH	144	if (ret)
c411e5f6 CH	145	return ret;
b9b2dd36	146	copy_to_if_dqblk(&idq, &fdq);
c411e5f6 CH	147	if (copy_to_user(addr, &idq, sizeof(idq)))
	148	return -EFAULT;
	149	return 0;
	150	}
	151
c472b432 CH	152	static void copy_from_if_dqblk(struct fs_disk_quota dst, struct if_dqblk src)
	153	{
	154	dst->d_blk_hardlimit = src->dqb_bhardlimit;
	155	dst->d_blk_softlimit = src->dqb_bsoftlimit;
	156	dst->d_bcount = src->dqb_curspace;
	157	dst->d_ino_hardlimit = src->dqb_ihardlimit;
	158	dst->d_ino_softlimit = src->dqb_isoftlimit;
	159	dst->d_icount = src->dqb_curinodes;
	160	dst->d_btimer = src->dqb_btime;
	161	dst->d_itimer = src->dqb_itime;
	162
	163	dst->d_fieldmask = 0;
	164	if (src->dqb_valid & QIF_BLIMITS)
	165	dst->d_fieldmask \|= FS_DQ_BSOFT \| FS_DQ_BHARD;
	166	if (src->dqb_valid & QIF_SPACE)
	167	dst->d_fieldmask \|= FS_DQ_BCOUNT;
	168	if (src->dqb_valid & QIF_ILIMITS)
	169	dst->d_fieldmask \|= FS_DQ_ISOFT \| FS_DQ_IHARD;
	170	if (src->dqb_valid & QIF_INODES)
	171	dst->d_fieldmask \|= FS_DQ_ICOUNT;
	172	if (src->dqb_valid & QIF_BTIME)
	173	dst->d_fieldmask \|= FS_DQ_BTIMER;
	174	if (src->dqb_valid & QIF_ITIME)
	175	dst->d_fieldmask \|= FS_DQ_ITIMER;
	176	}
	177
c411e5f6 CH	178	static int quota_setquota(struct super_block *sb, int type, qid_t id,
	179	void __user *addr)
	180	{
c472b432	181	struct fs_disk_quota fdq;
c411e5f6 CH	182	struct if_dqblk idq;
	183
	184	if (copy_from_user(&idq, addr, sizeof(idq)))
	185	return -EFAULT;
f450d4fe CH	186	if (!sb->s_qcop->set_dqblk)
f450d4fe CH	187	return -ENOSYS;
c472b432 CH	188	copy_from_if_dqblk(&fdq, &idq);
c472b432 CH	189	return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
c411e5f6 CH	190	}
	191
	192	static int quota_setxstate(struct super_block sb, int cmd, void __user addr)
	193	{
	194	__u32 flags;
	195
	196	if (copy_from_user(&flags, addr, sizeof(flags)))
	197	return -EFAULT;
f450d4fe CH	198	if (!sb->s_qcop->set_xstate)
f450d4fe CH	199	return -ENOSYS;
c411e5f6 CH	200	return sb->s_qcop->set_xstate(sb, flags, cmd);
	201	}
	202
	203	static int quota_getxstate(struct super_block sb, void __user addr)
	204	{
	205	struct fs_quota_stat fqs;
	206	int ret;
f450d4fe CH	207
	208	if (!sb->s_qcop->get_xstate)
	209	return -ENOSYS;
c411e5f6 CH	210	ret = sb->s_qcop->get_xstate(sb, &fqs);
	211	if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
	212	return -EFAULT;
	213	return ret;
	214	}
1da177e4	215
c411e5f6 CH	216	static int quota_setxquota(struct super_block *sb, int type, qid_t id,
	217	void __user *addr)
	218	{
	219	struct fs_disk_quota fdq;
	220
	221	if (copy_from_user(&fdq, addr, sizeof(fdq)))
	222	return -EFAULT;
c472b432	223	if (!sb->s_qcop->set_dqblk)
f450d4fe	224	return -ENOSYS;
c472b432	225	return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
c411e5f6 CH	226	}
	227
	228	static int quota_getxquota(struct super_block *sb, int type, qid_t id,
	229	void __user *addr)
	230	{
	231	struct fs_disk_quota fdq;
	232	int ret;
	233
b9b2dd36	234	if (!sb->s_qcop->get_dqblk)
f450d4fe	235	return -ENOSYS;
b9b2dd36	236	ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
c411e5f6 CH	237	if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
	238	return -EFAULT;
	239	return ret;
	240	}
	241
	242	/* Copy parameters and call proper function */
	243	static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
	244	void __user *addr)
	245	{
c988afb5 CH	246	int ret;
	247
	248	if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
	249	return -EINVAL;
	250	if (!sb->s_qcop)
	251	return -ENOSYS;
	252
	253	ret = check_quotactl_permission(sb, type, cmd, id);
	254	if (ret < 0)
	255	return ret;
	256
c411e5f6 CH	257	switch (cmd) {
	258	case Q_QUOTAON:
	259	return quota_quotaon(sb, type, cmd, id, addr);
	260	case Q_QUOTAOFF:
f450d4fe CH	261	if (!sb->s_qcop->quota_off)
f450d4fe CH	262	return -ENOSYS;
c411e5f6 CH	263	return sb->s_qcop->quota_off(sb, type, 0);
	264	case Q_GETFMT:
	265	return quota_getfmt(sb, type, addr);
	266	case Q_GETINFO:
	267	return quota_getinfo(sb, type, addr);
	268	case Q_SETINFO:
	269	return quota_setinfo(sb, type, addr);
	270	case Q_GETQUOTA:
	271	return quota_getquota(sb, type, id, addr);
	272	case Q_SETQUOTA:
	273	return quota_setquota(sb, type, id, addr);
	274	case Q_SYNC:
6ae09575 CH	275	if (!sb->s_qcop->quota_sync)
6ae09575 CH	276	return -ENOSYS;
5fb324ad	277	return sb->s_qcop->quota_sync(sb, type, 1);
c411e5f6 CH	278	case Q_XQUOTAON:
	279	case Q_XQUOTAOFF:
	280	case Q_XQUOTARM:
	281	return quota_setxstate(sb, cmd, addr);
	282	case Q_XGETQSTAT:
	283	return quota_getxstate(sb, addr);
	284	case Q_XSETQLIM:
	285	return quota_setxquota(sb, type, id, addr);
	286	case Q_XGETQUOTA:
	287	return quota_getxquota(sb, type, id, addr);
	288	case Q_XQUOTASYNC:
8c4e4acd CH	289	/* caller already holds s_umount */
	290	if (sb->s_flags & MS_RDONLY)
	291	return -EROFS;
	292	writeback_inodes_sb(sb);
	293	return 0;
c411e5f6	294	default:
f450d4fe	295	return -EINVAL;
1da177e4	296	}
1da177e4 LT	297	}
1da177e4 LT	298
9361401e DH	299	/*
	300	* look up a superblock on which quota ops will be performed
	301	* - use the name of a block device to find the superblock thereon
	302	*/
7a2435d8	303	static struct super_block quotactl_block(const char __user special)
9361401e DH	304	{
	305	#ifdef CONFIG_BLOCK
	306	struct block_device *bdev;
	307	struct super_block *sb;
	308	char *tmp = getname(special);
	309
	310	if (IS_ERR(tmp))
e231c2ee	311	return ERR_CAST(tmp);
9361401e DH	312	bdev = lookup_bdev(tmp);
	313	putname(tmp);
	314	if (IS_ERR(bdev))
e231c2ee	315	return ERR_CAST(bdev);
9361401e DH	316	sb = get_super(bdev);
	317	bdput(bdev);
	318	if (!sb)
	319	return ERR_PTR(-ENODEV);
	320
	321	return sb;
	322	#else
	323	return ERR_PTR(-ENODEV);
	324	#endif
	325	}
	326
1da177e4 LT	327	/*
	328	* This is the system call interface. This communicates with
	329	* the user-level programs. Currently this only supports diskquota
	330	* calls. Maybe we need to add the process quotas etc. in the future,
	331	* but we probably should use rlimits for that.
	332	*/
3cdad428 HC	333	SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
3cdad428 HC	334	qid_t, id, void __user *, addr)
1da177e4 LT	335	{
	336	uint cmds, type;
	337	struct super_block *sb = NULL;
1da177e4 LT	338	int ret;
	339
	340	cmds = cmd >> SUBCMDSHIFT;
	341	type = cmd & SUBCMDMASK;
	342
6ae09575 CH	343	/*
	344	* As a special case Q_SYNC can be called without a specific device.
	345	* It will iterate all superblocks that have quota enabled and call
	346	* the sync action on each of them.
	347	*/
	348	if (!special) {
	349	if (cmds == Q_SYNC)
	350	return quota_sync_all(type);
	351	return -ENODEV;
1da177e4 LT	352	}
1da177e4 LT	353
6ae09575 CH	354	sb = quotactl_block(special);
	355	if (IS_ERR(sb))
	356	return PTR_ERR(sb);
	357
c988afb5	358	ret = do_quotactl(sb, type, cmds, id, addr);
1da177e4	359
6ae09575	360	drop_super(sb);
1da177e4 LT	361	return ret;
1da177e4 LT	362	}