[mirror_ubuntu-artful-kernel.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,
		         struct path *path)
{
	if (!sb->s_qcop->quota_on && !sb->s_qcop->quota_on_meta)
		return -ENOSYS;
	if (sb->s_qcop->quota_on_meta)
		return sb->s_qcop->quota_on_meta(sb, type, id);
	if (IS_ERR(path))
		return PTR_ERR(path);
	return sb->s_qcop->quota_on(sb, type, id, path);
}

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, struct path *path)
{
	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, path);
	case Q_QUOTAOFF:
		if (!sb->s_qcop->quota_off)
			return -ENOSYS;
		return sb->s_qcop->quota_off(sb, type);
	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, WB_REASON_SYNC);
		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;
	struct path path, *pathp = 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;
	}

	/*
	 * Path for quotaon has to be resolved before grabbing superblock
	 * because that gets s_umount sem which is also possibly needed by path
	 * resolution (think about autofs) and thus deadlocks could arise.
	 */
	if (cmds == Q_QUOTAON) {
		ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
		if (ret)
			pathp = ERR_PTR(ret);
		else
			pathp = &path;
	}

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

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

	drop_super(sb);
	if (pathp && !IS_ERR(pathp))
		path_put(pathp);
	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	66	static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
f00c9e44	67	struct path *path)
1da177e4	68	{
f00c9e44 JK	69	if (!sb->s_qcop->quota_on && !sb->s_qcop->quota_on_meta)
	70	return -ENOSYS;
	71	if (sb->s_qcop->quota_on_meta)
	72	return sb->s_qcop->quota_on_meta(sb, type, id);
	73	if (IS_ERR(path))
	74	return PTR_ERR(path);
	75	return sb->s_qcop->quota_on(sb, type, id, path);
c411e5f6	76	}
1da177e4	77
c411e5f6 CH	78	static int quota_getfmt(struct super_block sb, int type, void __user addr)
	79	{
	80	__u32 fmt;
1da177e4	81
c411e5f6 CH	82	down_read(&sb_dqopt(sb)->dqptr_sem);
	83	if (!sb_has_quota_active(sb, type)) {
	84	up_read(&sb_dqopt(sb)->dqptr_sem);
	85	return -ESRCH;
	86	}
	87	fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
	88	up_read(&sb_dqopt(sb)->dqptr_sem);
	89	if (copy_to_user(addr, &fmt, sizeof(fmt)))
	90	return -EFAULT;
	91	return 0;
	92	}
1da177e4	93
c411e5f6 CH	94	static int quota_getinfo(struct super_block sb, int type, void __user addr)
	95	{
	96	struct if_dqinfo info;
	97	int ret;
1da177e4	98
f450d4fe CH	99	if (!sb->s_qcop->get_info)
f450d4fe CH	100	return -ENOSYS;
c411e5f6 CH	101	ret = sb->s_qcop->get_info(sb, type, &info);
	102	if (!ret && copy_to_user(addr, &info, sizeof(info)))
	103	return -EFAULT;
	104	return ret;
	105	}
1da177e4	106
c411e5f6 CH	107	static int quota_setinfo(struct super_block sb, int type, void __user addr)
	108	{
	109	struct if_dqinfo info;
1da177e4	110
c411e5f6 CH	111	if (copy_from_user(&info, addr, sizeof(info)))
c411e5f6 CH	112	return -EFAULT;
f450d4fe CH	113	if (!sb->s_qcop->set_info)
f450d4fe CH	114	return -ENOSYS;
c411e5f6 CH	115	return sb->s_qcop->set_info(sb, type, &info);
	116	}
	117
b9b2dd36 CH	118	static void copy_to_if_dqblk(struct if_dqblk dst, struct fs_disk_quota src)
	119	{
	120	dst->dqb_bhardlimit = src->d_blk_hardlimit;
	121	dst->dqb_bsoftlimit = src->d_blk_softlimit;
	122	dst->dqb_curspace = src->d_bcount;
	123	dst->dqb_ihardlimit = src->d_ino_hardlimit;
	124	dst->dqb_isoftlimit = src->d_ino_softlimit;
	125	dst->dqb_curinodes = src->d_icount;
	126	dst->dqb_btime = src->d_btimer;
	127	dst->dqb_itime = src->d_itimer;
	128	dst->dqb_valid = QIF_ALL;
	129	}
	130
c411e5f6 CH	131	static int quota_getquota(struct super_block *sb, int type, qid_t id,
	132	void __user *addr)
	133	{
b9b2dd36	134	struct fs_disk_quota fdq;
c411e5f6 CH	135	struct if_dqblk idq;
	136	int ret;
	137
f450d4fe CH	138	if (!sb->s_qcop->get_dqblk)
f450d4fe CH	139	return -ENOSYS;
b9b2dd36	140	ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
c411e5f6 CH	141	if (ret)
c411e5f6 CH	142	return ret;
b9b2dd36	143	copy_to_if_dqblk(&idq, &fdq);
c411e5f6 CH	144	if (copy_to_user(addr, &idq, sizeof(idq)))
	145	return -EFAULT;
	146	return 0;
	147	}
	148
c472b432 CH	149	static void copy_from_if_dqblk(struct fs_disk_quota dst, struct if_dqblk src)
	150	{
	151	dst->d_blk_hardlimit = src->dqb_bhardlimit;
	152	dst->d_blk_softlimit = src->dqb_bsoftlimit;
	153	dst->d_bcount = src->dqb_curspace;
	154	dst->d_ino_hardlimit = src->dqb_ihardlimit;
	155	dst->d_ino_softlimit = src->dqb_isoftlimit;
	156	dst->d_icount = src->dqb_curinodes;
	157	dst->d_btimer = src->dqb_btime;
	158	dst->d_itimer = src->dqb_itime;
	159
	160	dst->d_fieldmask = 0;
	161	if (src->dqb_valid & QIF_BLIMITS)
	162	dst->d_fieldmask \|= FS_DQ_BSOFT \| FS_DQ_BHARD;
	163	if (src->dqb_valid & QIF_SPACE)
	164	dst->d_fieldmask \|= FS_DQ_BCOUNT;
	165	if (src->dqb_valid & QIF_ILIMITS)
	166	dst->d_fieldmask \|= FS_DQ_ISOFT \| FS_DQ_IHARD;
	167	if (src->dqb_valid & QIF_INODES)
	168	dst->d_fieldmask \|= FS_DQ_ICOUNT;
	169	if (src->dqb_valid & QIF_BTIME)
	170	dst->d_fieldmask \|= FS_DQ_BTIMER;
	171	if (src->dqb_valid & QIF_ITIME)
	172	dst->d_fieldmask \|= FS_DQ_ITIMER;
	173	}
	174
c411e5f6 CH	175	static int quota_setquota(struct super_block *sb, int type, qid_t id,
	176	void __user *addr)
	177	{
c472b432	178	struct fs_disk_quota fdq;
c411e5f6 CH	179	struct if_dqblk idq;
	180
	181	if (copy_from_user(&idq, addr, sizeof(idq)))
	182	return -EFAULT;
f450d4fe CH	183	if (!sb->s_qcop->set_dqblk)
f450d4fe CH	184	return -ENOSYS;
c472b432 CH	185	copy_from_if_dqblk(&fdq, &idq);
c472b432 CH	186	return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
c411e5f6 CH	187	}
	188
	189	static int quota_setxstate(struct super_block sb, int cmd, void __user addr)
	190	{
	191	__u32 flags;
	192
	193	if (copy_from_user(&flags, addr, sizeof(flags)))
	194	return -EFAULT;
f450d4fe CH	195	if (!sb->s_qcop->set_xstate)
f450d4fe CH	196	return -ENOSYS;
c411e5f6 CH	197	return sb->s_qcop->set_xstate(sb, flags, cmd);
	198	}
	199
	200	static int quota_getxstate(struct super_block sb, void __user addr)
	201	{
	202	struct fs_quota_stat fqs;
	203	int ret;
f450d4fe CH	204
	205	if (!sb->s_qcop->get_xstate)
	206	return -ENOSYS;
c411e5f6 CH	207	ret = sb->s_qcop->get_xstate(sb, &fqs);
	208	if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
	209	return -EFAULT;
	210	return ret;
	211	}
1da177e4	212
c411e5f6 CH	213	static int quota_setxquota(struct super_block *sb, int type, qid_t id,
	214	void __user *addr)
	215	{
	216	struct fs_disk_quota fdq;
	217
	218	if (copy_from_user(&fdq, addr, sizeof(fdq)))
	219	return -EFAULT;
c472b432	220	if (!sb->s_qcop->set_dqblk)
f450d4fe	221	return -ENOSYS;
c472b432	222	return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
c411e5f6 CH	223	}
	224
	225	static int quota_getxquota(struct super_block *sb, int type, qid_t id,
	226	void __user *addr)
	227	{
	228	struct fs_disk_quota fdq;
	229	int ret;
	230
b9b2dd36	231	if (!sb->s_qcop->get_dqblk)
f450d4fe	232	return -ENOSYS;
b9b2dd36	233	ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
c411e5f6 CH	234	if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
	235	return -EFAULT;
	236	return ret;
	237	}
	238
	239	/* Copy parameters and call proper function */
	240	static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
f00c9e44	241	void __user addr, struct path path)
c411e5f6	242	{
c988afb5 CH	243	int ret;
	244
	245	if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
	246	return -EINVAL;
	247	if (!sb->s_qcop)
	248	return -ENOSYS;
	249
	250	ret = check_quotactl_permission(sb, type, cmd, id);
	251	if (ret < 0)
	252	return ret;
	253
c411e5f6 CH	254	switch (cmd) {
c411e5f6 CH	255	case Q_QUOTAON:
f00c9e44	256	return quota_quotaon(sb, type, cmd, id, path);
c411e5f6	257	case Q_QUOTAOFF:
f450d4fe CH	258	if (!sb->s_qcop->quota_off)
f450d4fe CH	259	return -ENOSYS;
307ae18a	260	return sb->s_qcop->quota_off(sb, type);
c411e5f6 CH	261	case Q_GETFMT:
	262	return quota_getfmt(sb, type, addr);
	263	case Q_GETINFO:
	264	return quota_getinfo(sb, type, addr);
	265	case Q_SETINFO:
	266	return quota_setinfo(sb, type, addr);
	267	case Q_GETQUOTA:
	268	return quota_getquota(sb, type, id, addr);
	269	case Q_SETQUOTA:
	270	return quota_setquota(sb, type, id, addr);
	271	case Q_SYNC:
6ae09575 CH	272	if (!sb->s_qcop->quota_sync)
6ae09575 CH	273	return -ENOSYS;
5fb324ad	274	return sb->s_qcop->quota_sync(sb, type, 1);
c411e5f6 CH	275	case Q_XQUOTAON:
	276	case Q_XQUOTAOFF:
	277	case Q_XQUOTARM:
	278	return quota_setxstate(sb, cmd, addr);
	279	case Q_XGETQSTAT:
	280	return quota_getxstate(sb, addr);
	281	case Q_XSETQLIM:
	282	return quota_setxquota(sb, type, id, addr);
	283	case Q_XGETQUOTA:
	284	return quota_getxquota(sb, type, id, addr);
	285	case Q_XQUOTASYNC:
8c4e4acd CH	286	/* caller already holds s_umount */
	287	if (sb->s_flags & MS_RDONLY)
	288	return -EROFS;
0e175a18	289	writeback_inodes_sb(sb, WB_REASON_SYNC);
8c4e4acd	290	return 0;
c411e5f6	291	default:
f450d4fe	292	return -EINVAL;
1da177e4	293	}
1da177e4 LT	294	}
1da177e4 LT	295
9361401e DH	296	/*
	297	* look up a superblock on which quota ops will be performed
	298	* - use the name of a block device to find the superblock thereon
	299	*/
7a2435d8	300	static struct super_block quotactl_block(const char __user special)
9361401e DH	301	{
	302	#ifdef CONFIG_BLOCK
	303	struct block_device *bdev;
	304	struct super_block *sb;
	305	char *tmp = getname(special);
	306
	307	if (IS_ERR(tmp))
e231c2ee	308	return ERR_CAST(tmp);
9361401e DH	309	bdev = lookup_bdev(tmp);
	310	putname(tmp);
	311	if (IS_ERR(bdev))
e231c2ee	312	return ERR_CAST(bdev);
9361401e DH	313	sb = get_super(bdev);
	314	bdput(bdev);
	315	if (!sb)
	316	return ERR_PTR(-ENODEV);
	317
	318	return sb;
	319	#else
	320	return ERR_PTR(-ENODEV);
	321	#endif
	322	}
	323
1da177e4 LT	324	/*
	325	* This is the system call interface. This communicates with
	326	* the user-level programs. Currently this only supports diskquota
	327	* calls. Maybe we need to add the process quotas etc. in the future,
	328	* but we probably should use rlimits for that.
	329	*/
3cdad428 HC	330	SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
3cdad428 HC	331	qid_t, id, void __user *, addr)
1da177e4 LT	332	{
	333	uint cmds, type;
	334	struct super_block *sb = NULL;
f00c9e44	335	struct path path, *pathp = NULL;
1da177e4 LT	336	int ret;
	337
	338	cmds = cmd >> SUBCMDSHIFT;
	339	type = cmd & SUBCMDMASK;
	340
6ae09575 CH	341	/*
	342	* As a special case Q_SYNC can be called without a specific device.
	343	* It will iterate all superblocks that have quota enabled and call
	344	* the sync action on each of them.
	345	*/
	346	if (!special) {
	347	if (cmds == Q_SYNC)
	348	return quota_sync_all(type);
	349	return -ENODEV;
1da177e4 LT	350	}
1da177e4 LT	351
f00c9e44 JK	352	/*
	353	* Path for quotaon has to be resolved before grabbing superblock
	354	* because that gets s_umount sem which is also possibly needed by path
	355	* resolution (think about autofs) and thus deadlocks could arise.
	356	*/
	357	if (cmds == Q_QUOTAON) {
815d405c	358	ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW\|LOOKUP_AUTOMOUNT, &path);
f00c9e44 JK	359	if (ret)
	360	pathp = ERR_PTR(ret);
	361	else
	362	pathp = &path;
	363	}
	364
6ae09575 CH	365	sb = quotactl_block(special);
	366	if (IS_ERR(sb))
	367	return PTR_ERR(sb);
	368
f00c9e44	369	ret = do_quotactl(sb, type, cmds, id, addr, pathp);
1da177e4	370
6ae09575	371	drop_super(sb);
f00c9e44 JK	372	if (pathp && !IS_ERR(pathp))
f00c9e44 JK	373	path_put(pathp);
1da177e4 LT	374	return ret;
1da177e4 LT	375	}