[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/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)) {
		ret = PTR_ERR(sb);
		goto out;
	}

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

	drop_super(sb);
out:
	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>
1da177e4 LT	15	#include <linux/syscalls.h>
16f7e0fe	16	#include <linux/capability.h>
be586bab	17	#include <linux/quotaops.h>
b716395e	18	#include <linux/types.h>
8c4e4acd	19	#include <linux/writeback.h>
1da177e4	20
c988afb5 CH	21	static int check_quotactl_permission(struct super_block *sb, int type, int cmd,
c988afb5 CH	22	qid_t id)
1da177e4	23	{
c988afb5 CH	24	switch (cmd) {
	25	/* these commands do not require any special privilegues */
	26	case Q_GETFMT:
	27	case Q_SYNC:
	28	case Q_GETINFO:
	29	case Q_XGETQSTAT:
	30	case Q_XQUOTASYNC:
	31	break;
	32	/* allow to query information for dquots we "own" */
	33	case Q_GETQUOTA:
	34	case Q_XGETQUOTA:
	35	if ((type == USRQUOTA && current_euid() == id) \|\|
	36	(type == GRPQUOTA && in_egroup_p(id)))
	37	break;
	38	/FALLTHROUGH/
	39	default:
1da177e4 LT	40	if (!capable(CAP_SYS_ADMIN))
	41	return -EPERM;
	42	}
	43
c988afb5	44	return security_quotactl(cmd, type, id, sb);
1da177e4 LT	45	}
1da177e4 LT	46
01a05b33 AV	47	static void quota_sync_one(struct super_block sb, void arg)
	48	{
	49	if (sb->s_qcop && sb->s_qcop->quota_sync)
	50	sb->s_qcop->quota_sync(sb, (int )arg, 1);
	51	}
	52
6ae09575	53	static int quota_sync_all(int type)
1da177e4	54	{
6ae09575 CH	55	int ret;
	56
	57	if (type >= MAXQUOTAS)
	58	return -EINVAL;
	59	ret = security_quotactl(Q_SYNC, type, 0, NULL);
01a05b33 AV	60	if (!ret)
	61	iterate_supers(quota_sync_one, &type);
	62	return ret;
1da177e4 LT	63	}
1da177e4 LT	64
c411e5f6	65	static int quota_quotaon(struct super_block *sb, int type, int cmd, qid_t id,
f00c9e44	66	struct path *path)
1da177e4	67	{
f00c9e44 JK	68	if (!sb->s_qcop->quota_on && !sb->s_qcop->quota_on_meta)
	69	return -ENOSYS;
	70	if (sb->s_qcop->quota_on_meta)
	71	return sb->s_qcop->quota_on_meta(sb, type, id);
	72	if (IS_ERR(path))
	73	return PTR_ERR(path);
	74	return sb->s_qcop->quota_on(sb, type, id, path);
c411e5f6	75	}
1da177e4	76
c411e5f6 CH	77	static int quota_getfmt(struct super_block sb, int type, void __user addr)
	78	{
	79	__u32 fmt;
1da177e4	80
c411e5f6 CH	81	down_read(&sb_dqopt(sb)->dqptr_sem);
	82	if (!sb_has_quota_active(sb, type)) {
	83	up_read(&sb_dqopt(sb)->dqptr_sem);
	84	return -ESRCH;
	85	}
	86	fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
	87	up_read(&sb_dqopt(sb)->dqptr_sem);
	88	if (copy_to_user(addr, &fmt, sizeof(fmt)))
	89	return -EFAULT;
	90	return 0;
	91	}
1da177e4	92
c411e5f6 CH	93	static int quota_getinfo(struct super_block sb, int type, void __user addr)
	94	{
	95	struct if_dqinfo info;
	96	int ret;
1da177e4	97
f450d4fe CH	98	if (!sb->s_qcop->get_info)
f450d4fe CH	99	return -ENOSYS;
c411e5f6 CH	100	ret = sb->s_qcop->get_info(sb, type, &info);
	101	if (!ret && copy_to_user(addr, &info, sizeof(info)))
	102	return -EFAULT;
	103	return ret;
	104	}
1da177e4	105
c411e5f6 CH	106	static int quota_setinfo(struct super_block sb, int type, void __user addr)
	107	{
	108	struct if_dqinfo info;
1da177e4	109
c411e5f6 CH	110	if (copy_from_user(&info, addr, sizeof(info)))
c411e5f6 CH	111	return -EFAULT;
f450d4fe CH	112	if (!sb->s_qcop->set_info)
f450d4fe CH	113	return -ENOSYS;
c411e5f6 CH	114	return sb->s_qcop->set_info(sb, type, &info);
	115	}
	116
b9b2dd36 CH	117	static void copy_to_if_dqblk(struct if_dqblk dst, struct fs_disk_quota src)
	118	{
	119	dst->dqb_bhardlimit = src->d_blk_hardlimit;
	120	dst->dqb_bsoftlimit = src->d_blk_softlimit;
	121	dst->dqb_curspace = src->d_bcount;
	122	dst->dqb_ihardlimit = src->d_ino_hardlimit;
	123	dst->dqb_isoftlimit = src->d_ino_softlimit;
	124	dst->dqb_curinodes = src->d_icount;
	125	dst->dqb_btime = src->d_btimer;
	126	dst->dqb_itime = src->d_itimer;
	127	dst->dqb_valid = QIF_ALL;
	128	}
	129
c411e5f6 CH	130	static int quota_getquota(struct super_block *sb, int type, qid_t id,
	131	void __user *addr)
	132	{
b9b2dd36	133	struct fs_disk_quota fdq;
c411e5f6 CH	134	struct if_dqblk idq;
	135	int ret;
	136
f450d4fe CH	137	if (!sb->s_qcop->get_dqblk)
f450d4fe CH	138	return -ENOSYS;
b9b2dd36	139	ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
c411e5f6 CH	140	if (ret)
c411e5f6 CH	141	return ret;
b9b2dd36	142	copy_to_if_dqblk(&idq, &fdq);
c411e5f6 CH	143	if (copy_to_user(addr, &idq, sizeof(idq)))
	144	return -EFAULT;
	145	return 0;
	146	}
	147
c472b432 CH	148	static void copy_from_if_dqblk(struct fs_disk_quota dst, struct if_dqblk src)
	149	{
	150	dst->d_blk_hardlimit = src->dqb_bhardlimit;
	151	dst->d_blk_softlimit = src->dqb_bsoftlimit;
	152	dst->d_bcount = src->dqb_curspace;
	153	dst->d_ino_hardlimit = src->dqb_ihardlimit;
	154	dst->d_ino_softlimit = src->dqb_isoftlimit;
	155	dst->d_icount = src->dqb_curinodes;
	156	dst->d_btimer = src->dqb_btime;
	157	dst->d_itimer = src->dqb_itime;
	158
	159	dst->d_fieldmask = 0;
	160	if (src->dqb_valid & QIF_BLIMITS)
	161	dst->d_fieldmask \|= FS_DQ_BSOFT \| FS_DQ_BHARD;
	162	if (src->dqb_valid & QIF_SPACE)
	163	dst->d_fieldmask \|= FS_DQ_BCOUNT;
	164	if (src->dqb_valid & QIF_ILIMITS)
	165	dst->d_fieldmask \|= FS_DQ_ISOFT \| FS_DQ_IHARD;
	166	if (src->dqb_valid & QIF_INODES)
	167	dst->d_fieldmask \|= FS_DQ_ICOUNT;
	168	if (src->dqb_valid & QIF_BTIME)
	169	dst->d_fieldmask \|= FS_DQ_BTIMER;
	170	if (src->dqb_valid & QIF_ITIME)
	171	dst->d_fieldmask \|= FS_DQ_ITIMER;
	172	}
	173
c411e5f6 CH	174	static int quota_setquota(struct super_block *sb, int type, qid_t id,
	175	void __user *addr)
	176	{
c472b432	177	struct fs_disk_quota fdq;
c411e5f6 CH	178	struct if_dqblk idq;
	179
	180	if (copy_from_user(&idq, addr, sizeof(idq)))
	181	return -EFAULT;
f450d4fe CH	182	if (!sb->s_qcop->set_dqblk)
f450d4fe CH	183	return -ENOSYS;
c472b432 CH	184	copy_from_if_dqblk(&fdq, &idq);
c472b432 CH	185	return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
c411e5f6 CH	186	}
	187
	188	static int quota_setxstate(struct super_block sb, int cmd, void __user addr)
	189	{
	190	__u32 flags;
	191
	192	if (copy_from_user(&flags, addr, sizeof(flags)))
	193	return -EFAULT;
f450d4fe CH	194	if (!sb->s_qcop->set_xstate)
f450d4fe CH	195	return -ENOSYS;
c411e5f6 CH	196	return sb->s_qcop->set_xstate(sb, flags, cmd);
	197	}
	198
	199	static int quota_getxstate(struct super_block sb, void __user addr)
	200	{
	201	struct fs_quota_stat fqs;
	202	int ret;
f450d4fe CH	203
	204	if (!sb->s_qcop->get_xstate)
	205	return -ENOSYS;
c411e5f6 CH	206	ret = sb->s_qcop->get_xstate(sb, &fqs);
	207	if (!ret && copy_to_user(addr, &fqs, sizeof(fqs)))
	208	return -EFAULT;
	209	return ret;
	210	}
1da177e4	211
c411e5f6 CH	212	static int quota_setxquota(struct super_block *sb, int type, qid_t id,
	213	void __user *addr)
	214	{
	215	struct fs_disk_quota fdq;
	216
	217	if (copy_from_user(&fdq, addr, sizeof(fdq)))
	218	return -EFAULT;
c472b432	219	if (!sb->s_qcop->set_dqblk)
f450d4fe	220	return -ENOSYS;
c472b432	221	return sb->s_qcop->set_dqblk(sb, type, id, &fdq);
c411e5f6 CH	222	}
	223
	224	static int quota_getxquota(struct super_block *sb, int type, qid_t id,
	225	void __user *addr)
	226	{
	227	struct fs_disk_quota fdq;
	228	int ret;
	229
b9b2dd36	230	if (!sb->s_qcop->get_dqblk)
f450d4fe	231	return -ENOSYS;
b9b2dd36	232	ret = sb->s_qcop->get_dqblk(sb, type, id, &fdq);
c411e5f6 CH	233	if (!ret && copy_to_user(addr, &fdq, sizeof(fdq)))
	234	return -EFAULT;
	235	return ret;
	236	}
	237
	238	/* Copy parameters and call proper function */
	239	static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
f00c9e44	240	void __user addr, struct path path)
c411e5f6	241	{
c988afb5 CH	242	int ret;
	243
	244	if (type >= (XQM_COMMAND(cmd) ? XQM_MAXQUOTAS : MAXQUOTAS))
	245	return -EINVAL;
	246	if (!sb->s_qcop)
	247	return -ENOSYS;
	248
	249	ret = check_quotactl_permission(sb, type, cmd, id);
	250	if (ret < 0)
	251	return ret;
	252
c411e5f6 CH	253	switch (cmd) {
c411e5f6 CH	254	case Q_QUOTAON:
f00c9e44	255	return quota_quotaon(sb, type, cmd, id, path);
c411e5f6	256	case Q_QUOTAOFF:
f450d4fe CH	257	if (!sb->s_qcop->quota_off)
f450d4fe CH	258	return -ENOSYS;
307ae18a	259	return sb->s_qcop->quota_off(sb, type);
c411e5f6 CH	260	case Q_GETFMT:
	261	return quota_getfmt(sb, type, addr);
	262	case Q_GETINFO:
	263	return quota_getinfo(sb, type, addr);
	264	case Q_SETINFO:
	265	return quota_setinfo(sb, type, addr);
	266	case Q_GETQUOTA:
	267	return quota_getquota(sb, type, id, addr);
	268	case Q_SETQUOTA:
	269	return quota_setquota(sb, type, id, addr);
	270	case Q_SYNC:
6ae09575 CH	271	if (!sb->s_qcop->quota_sync)
6ae09575 CH	272	return -ENOSYS;
5fb324ad	273	return sb->s_qcop->quota_sync(sb, type, 1);
c411e5f6 CH	274	case Q_XQUOTAON:
	275	case Q_XQUOTAOFF:
	276	case Q_XQUOTARM:
	277	return quota_setxstate(sb, cmd, addr);
	278	case Q_XGETQSTAT:
	279	return quota_getxstate(sb, addr);
	280	case Q_XSETQLIM:
	281	return quota_setxquota(sb, type, id, addr);
	282	case Q_XGETQUOTA:
	283	return quota_getxquota(sb, type, id, addr);
	284	case Q_XQUOTASYNC:
8c4e4acd CH	285	/* caller already holds s_umount */
	286	if (sb->s_flags & MS_RDONLY)
	287	return -EROFS;
0e175a18	288	writeback_inodes_sb(sb, WB_REASON_SYNC);
8c4e4acd	289	return 0;
c411e5f6	290	default:
f450d4fe	291	return -EINVAL;
1da177e4	292	}
1da177e4 LT	293	}
1da177e4 LT	294
9361401e DH	295	/*
	296	* look up a superblock on which quota ops will be performed
	297	* - use the name of a block device to find the superblock thereon
	298	*/
7a2435d8	299	static struct super_block quotactl_block(const char __user special)
9361401e DH	300	{
	301	#ifdef CONFIG_BLOCK
	302	struct block_device *bdev;
	303	struct super_block *sb;
	304	char *tmp = getname(special);
	305
	306	if (IS_ERR(tmp))
e231c2ee	307	return ERR_CAST(tmp);
9361401e DH	308	bdev = lookup_bdev(tmp);
	309	putname(tmp);
	310	if (IS_ERR(bdev))
e231c2ee	311	return ERR_CAST(bdev);
9361401e DH	312	sb = get_super(bdev);
	313	bdput(bdev);
	314	if (!sb)
	315	return ERR_PTR(-ENODEV);
	316
	317	return sb;
	318	#else
	319	return ERR_PTR(-ENODEV);
	320	#endif
	321	}
	322
1da177e4 LT	323	/*
	324	* This is the system call interface. This communicates with
	325	* the user-level programs. Currently this only supports diskquota
	326	* calls. Maybe we need to add the process quotas etc. in the future,
	327	* but we probably should use rlimits for that.
	328	*/
3cdad428 HC	329	SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
3cdad428 HC	330	qid_t, id, void __user *, addr)
1da177e4 LT	331	{
	332	uint cmds, type;
	333	struct super_block *sb = NULL;
f00c9e44	334	struct path path, *pathp = NULL;
1da177e4 LT	335	int ret;
	336
	337	cmds = cmd >> SUBCMDSHIFT;
	338	type = cmd & SUBCMDMASK;
	339
6ae09575 CH	340	/*
	341	* As a special case Q_SYNC can be called without a specific device.
	342	* It will iterate all superblocks that have quota enabled and call
	343	* the sync action on each of them.
	344	*/
	345	if (!special) {
	346	if (cmds == Q_SYNC)
	347	return quota_sync_all(type);
	348	return -ENODEV;
1da177e4 LT	349	}
1da177e4 LT	350
f00c9e44 JK	351	/*
	352	* Path for quotaon has to be resolved before grabbing superblock
	353	* because that gets s_umount sem which is also possibly needed by path
	354	* resolution (think about autofs) and thus deadlocks could arise.
	355	*/
	356	if (cmds == Q_QUOTAON) {
815d405c	357	ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW\|LOOKUP_AUTOMOUNT, &path);
f00c9e44 JK	358	if (ret)
	359	pathp = ERR_PTR(ret);
	360	else
	361	pathp = &path;
	362	}
	363
6ae09575	364	sb = quotactl_block(special);
0aaa6188 JK	365	if (IS_ERR(sb)) {
	366	ret = PTR_ERR(sb);
	367	goto out;
	368	}
6ae09575	369
f00c9e44	370	ret = do_quotactl(sb, type, cmds, id, addr, pathp);
1da177e4	371
6ae09575	372	drop_super(sb);
0aaa6188	373	out:
f00c9e44 JK	374	if (pathp && !IS_ERR(pathp))
f00c9e44 JK	375	path_put(pathp);
1da177e4 LT	376	return ret;
1da177e4 LT	377	}