[linux.git] / fs / 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/smp_lock.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/buffer_head.h>
#include <linux/capability.h>
#include <linux/quotaops.h>

/* Check validity of generic quotactl commands */
static int generic_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
{
	if (type >= MAXQUOTAS)
		return -EINVAL;
	if (!sb && cmd != Q_SYNC)
		return -ENODEV;
	/* Is operation supported? */
	if (sb && !sb->s_qcop)
		return -ENOSYS;

	switch (cmd) {
		case Q_GETFMT:
			break;
		case Q_QUOTAON:
			if (!sb->s_qcop->quota_on)
				return -ENOSYS;
			break;
		case Q_QUOTAOFF:
			if (!sb->s_qcop->quota_off)
				return -ENOSYS;
			break;
		case Q_SETINFO:
			if (!sb->s_qcop->set_info)
				return -ENOSYS;
			break;
		case Q_GETINFO:
			if (!sb->s_qcop->get_info)
				return -ENOSYS;
			break;
		case Q_SETQUOTA:
			if (!sb->s_qcop->set_dqblk)
				return -ENOSYS;
			break;
		case Q_GETQUOTA:
			if (!sb->s_qcop->get_dqblk)
				return -ENOSYS;
			break;
		case Q_SYNC:
			if (sb && !sb->s_qcop->quota_sync)
				return -ENOSYS;
			break;
		default:
			return -EINVAL;
	}

	/* Is quota turned on for commands which need it? */
	switch (cmd) {
		case Q_GETFMT:
		case Q_GETINFO:
		case Q_QUOTAOFF:
		case Q_SETINFO:
		case Q_SETQUOTA:
		case Q_GETQUOTA:
			/* This is just informative test so we are satisfied without a lock */
			if (!sb_has_quota_enabled(sb, type))
				return -ESRCH;
	}

	/* Check privileges */
	if (cmd == Q_GETQUOTA) {
		if (((type == USRQUOTA && current->euid != id) ||
		     (type == GRPQUOTA && !in_egroup_p(id))) &&
		    !capable(CAP_SYS_ADMIN))
			return -EPERM;
	}
	else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO)
		if (!capable(CAP_SYS_ADMIN))
			return -EPERM;

	return 0;
}

/* Check validity of XFS Quota Manager commands */
static int xqm_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
{
	if (type >= XQM_MAXQUOTAS)
		return -EINVAL;
	if (!sb)
		return -ENODEV;
	if (!sb->s_qcop)
		return -ENOSYS;

	switch (cmd) {
		case Q_XQUOTAON:
		case Q_XQUOTAOFF:
		case Q_XQUOTARM:
			if (!sb->s_qcop->set_xstate)
				return -ENOSYS;
			break;
		case Q_XGETQSTAT:
			if (!sb->s_qcop->get_xstate)
				return -ENOSYS;
			break;
		case Q_XSETQLIM:
			if (!sb->s_qcop->set_xquota)
				return -ENOSYS;
			break;
		case Q_XGETQUOTA:
			if (!sb->s_qcop->get_xquota)
				return -ENOSYS;
			break;
		case Q_XQUOTASYNC:
			if (!sb->s_qcop->quota_sync)
				return -ENOSYS;
			break;
		default:
			return -EINVAL;
	}

	/* Check privileges */
	if (cmd == Q_XGETQUOTA) {
		if (((type == XQM_USRQUOTA && current->euid != id) ||
		     (type == XQM_GRPQUOTA && !in_egroup_p(id))) &&
		     !capable(CAP_SYS_ADMIN))
			return -EPERM;
	} else if (cmd != Q_XGETQSTAT && cmd != Q_XQUOTASYNC) {
		if (!capable(CAP_SYS_ADMIN))
			return -EPERM;
	}

	return 0;
}

static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
{
	int error;

	if (XQM_COMMAND(cmd))
		error = xqm_quotactl_valid(sb, type, cmd, id);
	else
		error = generic_quotactl_valid(sb, type, cmd, id);
	if (!error)
		error = security_quotactl(cmd, type, id, sb);
	return error;
}

static void quota_sync_sb(struct super_block *sb, int type)
{
	int cnt;
	struct inode *discard[MAXQUOTAS];

	sb->s_qcop->quota_sync(sb, type);
	/* This is not very clever (and fast) but currently I don't know about
	 * any other simple way of getting quota data to disk and we must get
	 * them there for userspace to be visible... */
	if (sb->s_op->sync_fs)
		sb->s_op->sync_fs(sb, 1);
	sync_blockdev(sb->s_bdev);

	/* Now when everything is written we can discard the pagecache so
	 * that userspace sees the changes. We need i_mutex and so we could
	 * not do it inside dqonoff_mutex. Moreover we need to be carefull
	 * about races with quotaoff() (that is the reason why we have own
	 * reference to inode). */
	mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		discard[cnt] = NULL;
		if (type != -1 && cnt != type)
			continue;
		if (!sb_has_quota_enabled(sb, cnt))
			continue;
		discard[cnt] = igrab(sb_dqopt(sb)->files[cnt]);
	}
	mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
		if (discard[cnt]) {
			mutex_lock(&discard[cnt]->i_mutex);
			truncate_inode_pages(&discard[cnt]->i_data, 0);
			mutex_unlock(&discard[cnt]->i_mutex);
			iput(discard[cnt]);
		}
	}
}

void sync_dquots(struct super_block *sb, int type)
{
	int cnt, dirty;

	if (sb) {
		if (sb->s_qcop->quota_sync)
			quota_sync_sb(sb, type);
		return;
	}

	spin_lock(&sb_lock);
restart:
	list_for_each_entry(sb, &super_blocks, s_list) {
		/* This test just improves performance so it needn't be reliable... */
		for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++)
			if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt)
			    && info_any_dirty(&sb_dqopt(sb)->info[cnt]))
				dirty = 1;
		if (!dirty)
			continue;
		sb->s_count++;
		spin_unlock(&sb_lock);
		down_read(&sb->s_umount);
		if (sb->s_root && sb->s_qcop->quota_sync)
			quota_sync_sb(sb, type);
		up_read(&sb->s_umount);
		spin_lock(&sb_lock);
		if (__put_super_and_need_restart(sb))
			goto restart;
	}
	spin_unlock(&sb_lock);
}

/* 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;

	switch (cmd) {
		case Q_QUOTAON: {
			char *pathname;

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

		case Q_GETFMT: {
			__u32 fmt;

			down_read(&sb_dqopt(sb)->dqptr_sem);
			if (!sb_has_quota_enabled(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;
		}
		case Q_GETINFO: {
			struct if_dqinfo info;

			if ((ret = sb->s_qcop->get_info(sb, type, &info)))
				return ret;
			if (copy_to_user(addr, &info, sizeof(info)))
				return -EFAULT;
			return 0;
		}
		case Q_SETINFO: {
			struct if_dqinfo info;

			if (copy_from_user(&info, addr, sizeof(info)))
				return -EFAULT;
			return sb->s_qcop->set_info(sb, type, &info);
		}
		case Q_GETQUOTA: {
			struct if_dqblk idq;

			if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
				return ret;
			if (copy_to_user(addr, &idq, sizeof(idq)))
				return -EFAULT;
			return 0;
		}
		case Q_SETQUOTA: {
			struct if_dqblk idq;

			if (copy_from_user(&idq, addr, sizeof(idq)))
				return -EFAULT;
			return sb->s_qcop->set_dqblk(sb, type, id, &idq);
		}
		case Q_SYNC:
			sync_dquots(sb, type);
			return 0;

		case Q_XQUOTAON:
		case Q_XQUOTAOFF:
		case Q_XQUOTARM: {
			__u32 flags;

			if (copy_from_user(&flags, addr, sizeof(flags)))
				return -EFAULT;
			return sb->s_qcop->set_xstate(sb, flags, cmd);
		}
		case Q_XGETQSTAT: {
			struct fs_quota_stat fqs;
		
			if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
				return ret;
			if (copy_to_user(addr, &fqs, sizeof(fqs)))
				return -EFAULT;
			return 0;
		}
		case Q_XSETQLIM: {
			struct fs_disk_quota fdq;

			if (copy_from_user(&fdq, addr, sizeof(fdq)))
				return -EFAULT;
		       return sb->s_qcop->set_xquota(sb, type, id, &fdq);
		}
		case Q_XGETQUOTA: {
			struct fs_disk_quota fdq;

			if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
				return ret;
			if (copy_to_user(addr, &fdq, sizeof(fdq)))
				return -EFAULT;
			return 0;
		}
		case Q_XQUOTASYNC:
			return sb->s_qcop->quota_sync(sb, type);
		/* We never reach here unless validity check is broken */
		default:
			BUG();
	}
	return 0;
}

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

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

	if (cmds != Q_SYNC || special) {
		tmp = getname(special);
		if (IS_ERR(tmp))
			return PTR_ERR(tmp);
		bdev = lookup_bdev(tmp);
		putname(tmp);
		if (IS_ERR(bdev))
			return PTR_ERR(bdev);
		sb = get_super(bdev);
		bdput(bdev);
		if (!sb)
			return -ENODEV;
	}

	ret = check_quotactl_valid(sb, type, cmds, id);
	if (ret >= 0)
		ret = do_quotactl(sb, type, cmds, id, addr);
	if (sb)
		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>
	14	#include <linux/smp_lock.h>
	15	#include <linux/security.h>
	16	#include <linux/syscalls.h>
	17	#include <linux/buffer_head.h>
16f7e0fe	18	#include <linux/capability.h>
be586bab	19	#include <linux/quotaops.h>
1da177e4 LT	20
	21	/* Check validity of generic quotactl commands */
	22	static int generic_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
	23	{
	24	if (type >= MAXQUOTAS)
	25	return -EINVAL;
	26	if (!sb && cmd != Q_SYNC)
	27	return -ENODEV;
	28	/* Is operation supported? */
	29	if (sb && !sb->s_qcop)
	30	return -ENOSYS;
	31
	32	switch (cmd) {
	33	case Q_GETFMT:
	34	break;
	35	case Q_QUOTAON:
	36	if (!sb->s_qcop->quota_on)
	37	return -ENOSYS;
	38	break;
	39	case Q_QUOTAOFF:
	40	if (!sb->s_qcop->quota_off)
	41	return -ENOSYS;
	42	break;
	43	case Q_SETINFO:
	44	if (!sb->s_qcop->set_info)
	45	return -ENOSYS;
	46	break;
	47	case Q_GETINFO:
	48	if (!sb->s_qcop->get_info)
	49	return -ENOSYS;
	50	break;
	51	case Q_SETQUOTA:
	52	if (!sb->s_qcop->set_dqblk)
	53	return -ENOSYS;
	54	break;
	55	case Q_GETQUOTA:
	56	if (!sb->s_qcop->get_dqblk)
	57	return -ENOSYS;
	58	break;
	59	case Q_SYNC:
	60	if (sb && !sb->s_qcop->quota_sync)
	61	return -ENOSYS;
	62	break;
	63	default:
	64	return -EINVAL;
	65	}
	66
	67	/* Is quota turned on for commands which need it? */
	68	switch (cmd) {
	69	case Q_GETFMT:
	70	case Q_GETINFO:
	71	case Q_QUOTAOFF:
	72	case Q_SETINFO:
	73	case Q_SETQUOTA:
	74	case Q_GETQUOTA:
	75	/* This is just informative test so we are satisfied without a lock */
	76	if (!sb_has_quota_enabled(sb, type))
	77	return -ESRCH;
	78	}
	79
	80	/* Check privileges */
	81	if (cmd == Q_GETQUOTA) {
	82	if (((type == USRQUOTA && current->euid != id) \|\|
	83	(type == GRPQUOTA && !in_egroup_p(id))) &&
84	!capable(CAP_SYS_ADMIN))
85	return -EPERM;
86	}
87	else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO)
88	if (!capable(CAP_SYS_ADMIN))
89	return -EPERM;
90
91	return 0;
92	}
93
94	/* Check validity of XFS Quota Manager commands */
95	static int xqm_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
96	{
97	if (type >= XQM_MAXQUOTAS)
98	return -EINVAL;
99	if (!sb)
100	return -ENODEV;
101	if (!sb->s_qcop)
102	return -ENOSYS;
103
104	switch (cmd) {
105	case Q_XQUOTAON:
106	case Q_XQUOTAOFF:
107	case Q_XQUOTARM:
108	if (!sb->s_qcop->set_xstate)
109	return -ENOSYS;
110	break;
111	case Q_XGETQSTAT:
112	if (!sb->s_qcop->get_xstate)
113	return -ENOSYS;
114	break;
115	case Q_XSETQLIM:
116	if (!sb->s_qcop->set_xquota)
117	return -ENOSYS;
118	break;
119	case Q_XGETQUOTA:
120	if (!sb->s_qcop->get_xquota)
121	return -ENOSYS;
122	break;
de69e5f4 NS	123	case Q_XQUOTASYNC:
	124	if (!sb->s_qcop->quota_sync)
	125	return -ENOSYS;
	126	break;
1da177e4 LT	127	default:
	128	return -EINVAL;
	129	}
	130
	131	/* Check privileges */
	132	if (cmd == Q_XGETQUOTA) {
	133	if (((type == XQM_USRQUOTA && current->euid != id) \|\|
	134	(type == XQM_GRPQUOTA && !in_egroup_p(id))) &&
	135	!capable(CAP_SYS_ADMIN))
	136	return -EPERM;
de69e5f4	137	} else if (cmd != Q_XGETQSTAT && cmd != Q_XQUOTASYNC) {
1da177e4 LT	138	if (!capable(CAP_SYS_ADMIN))
	139	return -EPERM;
	140	}
	141
	142	return 0;
	143	}
	144
	145	static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
	146	{
	147	int error;
	148
	149	if (XQM_COMMAND(cmd))
	150	error = xqm_quotactl_valid(sb, type, cmd, id);
	151	else
	152	error = generic_quotactl_valid(sb, type, cmd, id);
	153	if (!error)
	154	error = security_quotactl(cmd, type, id, sb);
	155	return error;
	156	}
	157
1da177e4 LT	158	static void quota_sync_sb(struct super_block *sb, int type)
	159	{
	160	int cnt;
	161	struct inode *discard[MAXQUOTAS];
	162
	163	sb->s_qcop->quota_sync(sb, type);
	164	/* This is not very clever (and fast) but currently I don't know about
	165	* any other simple way of getting quota data to disk and we must get
	166	* them there for userspace to be visible... */
	167	if (sb->s_op->sync_fs)
	168	sb->s_op->sync_fs(sb, 1);
	169	sync_blockdev(sb->s_bdev);
	170
	171	/* Now when everything is written we can discard the pagecache so
1b1dcc1b	172	* that userspace sees the changes. We need i_mutex and so we could
d3be915f	173	* not do it inside dqonoff_mutex. Moreover we need to be carefull
1da177e4 LT	174	* about races with quotaoff() (that is the reason why we have own
1da177e4 LT	175	* reference to inode). */
d3be915f	176	mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
1da177e4 LT	177	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
	178	discard[cnt] = NULL;
	179	if (type != -1 && cnt != type)
	180	continue;
	181	if (!sb_has_quota_enabled(sb, cnt))
	182	continue;
	183	discard[cnt] = igrab(sb_dqopt(sb)->files[cnt]);
	184	}
d3be915f	185	mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
1da177e4 LT	186	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
1da177e4 LT	187	if (discard[cnt]) {
1b1dcc1b	188	mutex_lock(&discard[cnt]->i_mutex);
1da177e4	189	truncate_inode_pages(&discard[cnt]->i_data, 0);
1b1dcc1b	190	mutex_unlock(&discard[cnt]->i_mutex);
1da177e4 LT	191	iput(discard[cnt]);
	192	}
	193	}
	194	}
	195
	196	void sync_dquots(struct super_block *sb, int type)
	197	{
618f0636 KK	198	int cnt, dirty;
618f0636 KK	199
1da177e4 LT	200	if (sb) {
	201	if (sb->s_qcop->quota_sync)
	202	quota_sync_sb(sb, type);
618f0636	203	return;
1da177e4	204	}
618f0636 KK	205
	206	spin_lock(&sb_lock);
	207	restart:
	208	list_for_each_entry(sb, &super_blocks, s_list) {
	209	/* This test just improves performance so it needn't be reliable... */
	210	for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++)
	211	if ((type == cnt \|\| type == -1) && sb_has_quota_enabled(sb, cnt)
	212	&& info_any_dirty(&sb_dqopt(sb)->info[cnt]))
	213	dirty = 1;
	214	if (!dirty)
	215	continue;
	216	sb->s_count++;
	217	spin_unlock(&sb_lock);
	218	down_read(&sb->s_umount);
	219	if (sb->s_root && sb->s_qcop->quota_sync)
	220	quota_sync_sb(sb, type);
	221	up_read(&sb->s_umount);
	222	spin_lock(&sb_lock);
	223	if (__put_super_and_need_restart(sb))
	224	goto restart;
1da177e4	225	}
618f0636	226	spin_unlock(&sb_lock);
1da177e4 LT	227	}
	228
	229	/* Copy parameters and call proper function */
	230	static int do_quotactl(struct super_block sb, int type, int cmd, qid_t id, void __user addr)
	231	{
	232	int ret;
	233
	234	switch (cmd) {
	235	case Q_QUOTAON: {
	236	char *pathname;
	237
	238	if (IS_ERR(pathname = getname(addr)))
	239	return PTR_ERR(pathname);
	240	ret = sb->s_qcop->quota_on(sb, type, id, pathname);
	241	putname(pathname);
	242	return ret;
	243	}
	244	case Q_QUOTAOFF:
	245	return sb->s_qcop->quota_off(sb, type);
	246
	247	case Q_GETFMT: {
	248	__u32 fmt;
	249
	250	down_read(&sb_dqopt(sb)->dqptr_sem);
	251	if (!sb_has_quota_enabled(sb, type)) {
	252	up_read(&sb_dqopt(sb)->dqptr_sem);
	253	return -ESRCH;
	254	}
	255	fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
	256	up_read(&sb_dqopt(sb)->dqptr_sem);
	257	if (copy_to_user(addr, &fmt, sizeof(fmt)))
	258	return -EFAULT;
	259	return 0;
	260	}
	261	case Q_GETINFO: {
	262	struct if_dqinfo info;
	263
	264	if ((ret = sb->s_qcop->get_info(sb, type, &info)))
	265	return ret;
	266	if (copy_to_user(addr, &info, sizeof(info)))
	267	return -EFAULT;
	268	return 0;
	269	}
	270	case Q_SETINFO: {
	271	struct if_dqinfo info;
	272
	273	if (copy_from_user(&info, addr, sizeof(info)))
	274	return -EFAULT;
	275	return sb->s_qcop->set_info(sb, type, &info);
	276	}
	277	case Q_GETQUOTA: {
	278	struct if_dqblk idq;
	279
	280	if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
	281	return ret;
	282	if (copy_to_user(addr, &idq, sizeof(idq)))
	283	return -EFAULT;
	284	return 0;
	285	}
	286	case Q_SETQUOTA: {
	287	struct if_dqblk idq;
	288
	289	if (copy_from_user(&idq, addr, sizeof(idq)))
	290	return -EFAULT;
291	return sb->s_qcop->set_dqblk(sb, type, id, &idq);
292	}
293	case Q_SYNC:
294	sync_dquots(sb, type);
295	return 0;
296
297	case Q_XQUOTAON:
298	case Q_XQUOTAOFF:
299	case Q_XQUOTARM: {
300	__u32 flags;
301
302	if (copy_from_user(&flags, addr, sizeof(flags)))
303	return -EFAULT;
304	return sb->s_qcop->set_xstate(sb, flags, cmd);
305	}
306	case Q_XGETQSTAT: {
307	struct fs_quota_stat fqs;
308
309	if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
310	return ret;
311	if (copy_to_user(addr, &fqs, sizeof(fqs)))
312	return -EFAULT;
313	return 0;
314	}
315	case Q_XSETQLIM: {
316	struct fs_disk_quota fdq;
317
318	if (copy_from_user(&fdq, addr, sizeof(fdq)))
319	return -EFAULT;
320	return sb->s_qcop->set_xquota(sb, type, id, &fdq);
321	}
322	case Q_XGETQUOTA: {
323	struct fs_disk_quota fdq;
324
325	if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
326	return ret;
327	if (copy_to_user(addr, &fdq, sizeof(fdq)))
328	return -EFAULT;
329	return 0;
330	}
de69e5f4 NS	331	case Q_XQUOTASYNC:
de69e5f4 NS	332	return sb->s_qcop->quota_sync(sb, type);
1da177e4 LT	333	/* We never reach here unless validity check is broken */
	334	default:
	335	BUG();
	336	}
	337	return 0;
	338	}
	339
	340	/*
	341	* This is the system call interface. This communicates with
	342	* the user-level programs. Currently this only supports diskquota
	343	* calls. Maybe we need to add the process quotas etc. in the future,
	344	* but we probably should use rlimits for that.
	345	*/
	346	asmlinkage long sys_quotactl(unsigned int cmd, const char __user special, qid_t id, void __user addr)
	347	{
	348	uint cmds, type;
	349	struct super_block *sb = NULL;
	350	struct block_device *bdev;
	351	char *tmp;
	352	int ret;
	353
	354	cmds = cmd >> SUBCMDSHIFT;
	355	type = cmd & SUBCMDMASK;
	356
	357	if (cmds != Q_SYNC \|\| special) {
	358	tmp = getname(special);
	359	if (IS_ERR(tmp))
	360	return PTR_ERR(tmp);
	361	bdev = lookup_bdev(tmp);
	362	putname(tmp);
	363	if (IS_ERR(bdev))
	364	return PTR_ERR(bdev);
	365	sb = get_super(bdev);
	366	bdput(bdev);
	367	if (!sb)
	368	return -ENODEV;
	369	}
	370
	371	ret = check_quotactl_valid(sb, type, cmds, id);
	372	if (ret >= 0)
	373	ret = do_quotactl(sb, type, cmds, id, addr);
	374	if (sb)
	375	drop_super(sb);
	376
	377	return ret;
	378	}