[mirror_ubuntu-focal-kernel.git] / fs / fuse / control.c

/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2008  Miklos Szeredi <miklos@szeredi.hu>

  This program can be distributed under the terms of the GNU GPL.
  See the file COPYING.
*/

#include "fuse_i.h"

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs_context.h>

#define FUSE_CTL_SUPER_MAGIC 0x65735543

/*
 * This is non-NULL when the single instance of the control filesystem
 * exists.  Protected by fuse_mutex
 */
static struct super_block *fuse_control_sb;

static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file)
{
	struct fuse_conn *fc;
	mutex_lock(&fuse_mutex);
	fc = file_inode(file)->i_private;
	if (fc)
		fc = fuse_conn_get(fc);
	mutex_unlock(&fuse_mutex);
	return fc;
}

static ssize_t fuse_conn_abort_write(struct file *file, const char __user *buf,
				     size_t count, loff_t *ppos)
{
	struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
	if (fc) {
		if (fc->abort_err)
			fc->aborted = true;
		fuse_abort_conn(fc);
		fuse_conn_put(fc);
	}
	return count;
}

static ssize_t fuse_conn_waiting_read(struct file *file, char __user *buf,
				      size_t len, loff_t *ppos)
{
	char tmp[32];
	size_t size;

	if (!*ppos) {
		long value;
		struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
		if (!fc)
			return 0;

		value = atomic_read(&fc->num_waiting);
		file->private_data = (void *)value;
		fuse_conn_put(fc);
	}
	size = sprintf(tmp, "%ld\n", (long)file->private_data);
	return simple_read_from_buffer(buf, len, ppos, tmp, size);
}

static ssize_t fuse_conn_limit_read(struct file *file, char __user *buf,
				    size_t len, loff_t *ppos, unsigned val)
{
	char tmp[32];
	size_t size = sprintf(tmp, "%u\n", val);

	return simple_read_from_buffer(buf, len, ppos, tmp, size);
}

static ssize_t fuse_conn_limit_write(struct file *file, const char __user *buf,
				     size_t count, loff_t *ppos, unsigned *val,
				     unsigned global_limit)
{
	unsigned long t;
	unsigned limit = (1 << 16) - 1;
	int err;

	if (*ppos)
		return -EINVAL;

	err = kstrtoul_from_user(buf, count, 0, &t);
	if (err)
		return err;

	if (!capable(CAP_SYS_ADMIN))
		limit = min(limit, global_limit);

	if (t > limit)
		return -EINVAL;

	*val = t;

	return count;
}

static ssize_t fuse_conn_max_background_read(struct file *file,
					     char __user *buf, size_t len,
					     loff_t *ppos)
{
	struct fuse_conn *fc;
	unsigned val;

	fc = fuse_ctl_file_conn_get(file);
	if (!fc)
		return 0;

	val = READ_ONCE(fc->max_background);
	fuse_conn_put(fc);

	return fuse_conn_limit_read(file, buf, len, ppos, val);
}

static ssize_t fuse_conn_max_background_write(struct file *file,
					      const char __user *buf,
					      size_t count, loff_t *ppos)
{
	unsigned uninitialized_var(val);
	ssize_t ret;

	ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
				    max_user_bgreq);
	if (ret > 0) {
		struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
		if (fc) {
			spin_lock(&fc->bg_lock);
			fc->max_background = val;
			fc->blocked = fc->num_background >= fc->max_background;
			if (!fc->blocked)
				wake_up(&fc->blocked_waitq);
			spin_unlock(&fc->bg_lock);
			fuse_conn_put(fc);
		}
	}

	return ret;
}

static ssize_t fuse_conn_congestion_threshold_read(struct file *file,
						   char __user *buf, size_t len,
						   loff_t *ppos)
{
	struct fuse_conn *fc;
	unsigned val;

	fc = fuse_ctl_file_conn_get(file);
	if (!fc)
		return 0;

	val = READ_ONCE(fc->congestion_threshold);
	fuse_conn_put(fc);

	return fuse_conn_limit_read(file, buf, len, ppos, val);
}

static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
						    const char __user *buf,
						    size_t count, loff_t *ppos)
{
	unsigned uninitialized_var(val);
	struct fuse_conn *fc;
	ssize_t ret;

	ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
				    max_user_congthresh);
	if (ret <= 0)
		goto out;
	fc = fuse_ctl_file_conn_get(file);
	if (!fc)
		goto out;

	spin_lock(&fc->bg_lock);
	fc->congestion_threshold = val;
	if (fc->sb) {
		if (fc->num_background < fc->congestion_threshold) {
			clear_bdi_congested(fc->sb->s_bdi, BLK_RW_SYNC);
			clear_bdi_congested(fc->sb->s_bdi, BLK_RW_ASYNC);
		} else {
			set_bdi_congested(fc->sb->s_bdi, BLK_RW_SYNC);
			set_bdi_congested(fc->sb->s_bdi, BLK_RW_ASYNC);
		}
	}
	spin_unlock(&fc->bg_lock);
	fuse_conn_put(fc);
out:
	return ret;
}

static const struct file_operations fuse_ctl_abort_ops = {
	.open = nonseekable_open,
	.write = fuse_conn_abort_write,
	.llseek = no_llseek,
};

static const struct file_operations fuse_ctl_waiting_ops = {
	.open = nonseekable_open,
	.read = fuse_conn_waiting_read,
	.llseek = no_llseek,
};

static const struct file_operations fuse_conn_max_background_ops = {
	.open = nonseekable_open,
	.read = fuse_conn_max_background_read,
	.write = fuse_conn_max_background_write,
	.llseek = no_llseek,
};

static const struct file_operations fuse_conn_congestion_threshold_ops = {
	.open = nonseekable_open,
	.read = fuse_conn_congestion_threshold_read,
	.write = fuse_conn_congestion_threshold_write,
	.llseek = no_llseek,
};

static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
					  struct fuse_conn *fc,
					  const char *name,
					  int mode, int nlink,
					  const struct inode_operations *iop,
					  const struct file_operations *fop)
{
	struct dentry *dentry;
	struct inode *inode;

	BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
	dentry = d_alloc_name(parent, name);
	if (!dentry)
		return NULL;

	inode = new_inode(fuse_control_sb);
	if (!inode) {
		dput(dentry);
		return NULL;
	}

	inode->i_ino = get_next_ino();
	inode->i_mode = mode;
	inode->i_uid = fc->user_id;
	inode->i_gid = fc->group_id;
	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
	/* setting ->i_op to NULL is not allowed */
	if (iop)
		inode->i_op = iop;
	inode->i_fop = fop;
	set_nlink(inode, nlink);
	inode->i_private = fc;
	d_add(dentry, inode);

	fc->ctl_dentry[fc->ctl_ndents++] = dentry;

	return dentry;
}

/*
 * Add a connection to the control filesystem (if it exists).  Caller
 * must hold fuse_mutex
 */
int fuse_ctl_add_conn(struct fuse_conn *fc)
{
	struct dentry *parent;
	char name[32];

	if (!fuse_control_sb)
		return 0;

	parent = fuse_control_sb->s_root;
	inc_nlink(d_inode(parent));
	sprintf(name, "%u", fc->dev);
	parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2,
				     &simple_dir_inode_operations,
				     &simple_dir_operations);
	if (!parent)
		goto err;

	if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1,
				 NULL, &fuse_ctl_waiting_ops) ||
	    !fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1,
				 NULL, &fuse_ctl_abort_ops) ||
	    !fuse_ctl_add_dentry(parent, fc, "max_background", S_IFREG | 0600,
				 1, NULL, &fuse_conn_max_background_ops) ||
	    !fuse_ctl_add_dentry(parent, fc, "congestion_threshold",
				 S_IFREG | 0600, 1, NULL,
				 &fuse_conn_congestion_threshold_ops))
		goto err;

	return 0;

 err:
	fuse_ctl_remove_conn(fc);
	return -ENOMEM;
}

/*
 * Remove a connection from the control filesystem (if it exists).
 * Caller must hold fuse_mutex
 */
void fuse_ctl_remove_conn(struct fuse_conn *fc)
{
	int i;

	if (!fuse_control_sb)
		return;

	for (i = fc->ctl_ndents - 1; i >= 0; i--) {
		struct dentry *dentry = fc->ctl_dentry[i];
		d_inode(dentry)->i_private = NULL;
		if (!i) {
			/* Get rid of submounts: */
			d_invalidate(dentry);
		}
		dput(dentry);
	}
	drop_nlink(d_inode(fuse_control_sb->s_root));
}

static int fuse_ctl_fill_super(struct super_block *sb, struct fs_context *fctx)
{
	static const struct tree_descr empty_descr = {""};
	struct fuse_conn *fc;
	int err;

	err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
	if (err)
		return err;

	mutex_lock(&fuse_mutex);
	BUG_ON(fuse_control_sb);
	fuse_control_sb = sb;
	list_for_each_entry(fc, &fuse_conn_list, entry) {
		err = fuse_ctl_add_conn(fc);
		if (err) {
			fuse_control_sb = NULL;
			mutex_unlock(&fuse_mutex);
			return err;
		}
	}
	mutex_unlock(&fuse_mutex);

	return 0;
}

static int fuse_ctl_get_tree(struct fs_context *fc)
{
	return get_tree_single(fc, fuse_ctl_fill_super);
}

static const struct fs_context_operations fuse_ctl_context_ops = {
	.get_tree	= fuse_ctl_get_tree,
};

static int fuse_ctl_init_fs_context(struct fs_context *fc)
{
	fc->ops = &fuse_ctl_context_ops;
	return 0;
}

static void fuse_ctl_kill_sb(struct super_block *sb)
{
	struct fuse_conn *fc;

	mutex_lock(&fuse_mutex);
	fuse_control_sb = NULL;
	list_for_each_entry(fc, &fuse_conn_list, entry)
		fc->ctl_ndents = 0;
	mutex_unlock(&fuse_mutex);

	kill_litter_super(sb);
}

static struct file_system_type fuse_ctl_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "fusectl",
	.init_fs_context = fuse_ctl_init_fs_context,
	.kill_sb	= fuse_ctl_kill_sb,
};
MODULE_ALIAS_FS("fusectl");

int __init fuse_ctl_init(void)
{
	return register_filesystem(&fuse_ctl_fs_type);
}

void __exit fuse_ctl_cleanup(void)
{
	unregister_filesystem(&fuse_ctl_fs_type);
}
Commit	Line	Data
bafa9654 MS	1	/*
bafa9654 MS	2	FUSE: Filesystem in Userspace
1729a16c	3	Copyright (C) 2001-2008 Miklos Szeredi <miklos@szeredi.hu>
bafa9654 MS	4
	5	This program can be distributed under the terms of the GNU GPL.
	6	See the file COPYING.
	7	*/
	8
	9	#include "fuse_i.h"
	10
	11	#include <linux/init.h>
	12	#include <linux/module.h>
29cc02d9	13	#include <linux/fs_context.h>
bafa9654 MS	14
	15	#define FUSE_CTL_SUPER_MAGIC 0x65735543
	16
	17	/*
	18	* This is non-NULL when the single instance of the control filesystem
	19	* exists. Protected by fuse_mutex
	20	*/
	21	static struct super_block *fuse_control_sb;
	22
	23	static struct fuse_conn fuse_ctl_file_conn_get(struct file file)
	24	{
	25	struct fuse_conn *fc;
	26	mutex_lock(&fuse_mutex);
496ad9aa	27	fc = file_inode(file)->i_private;
bafa9654 MS	28	if (fc)
	29	fc = fuse_conn_get(fc);
	30	mutex_unlock(&fuse_mutex);
	31	return fc;
	32	}
	33
	34	static ssize_t fuse_conn_abort_write(struct file file, const char __user buf,
	35	size_t count, loff_t *ppos)
	36	{
	37	struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
	38	if (fc) {
eb98e3bd MS	39	if (fc->abort_err)
	40	fc->aborted = true;
	41	fuse_abort_conn(fc);
bafa9654 MS	42	fuse_conn_put(fc);
	43	}
	44	return count;
	45	}
	46
	47	static ssize_t fuse_conn_waiting_read(struct file file, char __user buf,
	48	size_t len, loff_t *ppos)
	49	{
	50	char tmp[32];
	51	size_t size;
	52
	53	if (!*ppos) {
1729a16c	54	long value;
bafa9654 MS	55	struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
	56	if (!fc)
	57	return 0;
	58
1729a16c MS	59	value = atomic_read(&fc->num_waiting);
1729a16c MS	60	file->private_data = (void *)value;
bafa9654 MS	61	fuse_conn_put(fc);
	62	}
	63	size = sprintf(tmp, "%ld\n", (long)file->private_data);
	64	return simple_read_from_buffer(buf, len, ppos, tmp, size);
	65	}
	66
79a9d994 CH	67	static ssize_t fuse_conn_limit_read(struct file file, char __user buf,
	68	size_t len, loff_t *ppos, unsigned val)
	69	{
	70	char tmp[32];
	71	size_t size = sprintf(tmp, "%u\n", val);
	72
	73	return simple_read_from_buffer(buf, len, ppos, tmp, size);
	74	}
	75
	76	static ssize_t fuse_conn_limit_write(struct file file, const char __user buf,
	77	size_t count, loff_t ppos, unsigned val,
	78	unsigned global_limit)
	79	{
	80	unsigned long t;
79a9d994 CH	81	unsigned limit = (1 << 16) - 1;
	82	int err;
	83
e2690695	84	if (*ppos)
79a9d994 CH	85	return -EINVAL;
79a9d994 CH	86
e2690695	87	err = kstrtoul_from_user(buf, count, 0, &t);
79a9d994 CH	88	if (err)
	89	return err;
	90
	91	if (!capable(CAP_SYS_ADMIN))
	92	limit = min(limit, global_limit);
	93
	94	if (t > limit)
	95	return -EINVAL;
	96
	97	*val = t;
	98
	99	return count;
	100	}
	101
	102	static ssize_t fuse_conn_max_background_read(struct file *file,
	103	char __user *buf, size_t len,
	104	loff_t *ppos)
	105	{
	106	struct fuse_conn *fc;
	107	unsigned val;
	108
	109	fc = fuse_ctl_file_conn_get(file);
	110	if (!fc)
	111	return 0;
	112
2a23f2b8	113	val = READ_ONCE(fc->max_background);
79a9d994 CH	114	fuse_conn_put(fc);
	115
	116	return fuse_conn_limit_read(file, buf, len, ppos, val);
	117	}
	118
	119	static ssize_t fuse_conn_max_background_write(struct file *file,
	120	const char __user *buf,
	121	size_t count, loff_t *ppos)
	122	{
381bf7ca	123	unsigned uninitialized_var(val);
79a9d994 CH	124	ssize_t ret;
	125
	126	ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
	127	max_user_bgreq);
	128	if (ret > 0) {
	129	struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
	130	if (fc) {
ae2dffa3	131	spin_lock(&fc->bg_lock);
79a9d994	132	fc->max_background = val;
2b30a533 KT	133	fc->blocked = fc->num_background >= fc->max_background;
	134	if (!fc->blocked)
	135	wake_up(&fc->blocked_waitq);
ae2dffa3	136	spin_unlock(&fc->bg_lock);
79a9d994 CH	137	fuse_conn_put(fc);
	138	}
	139	}
	140
	141	return ret;
	142	}
	143
	144	static ssize_t fuse_conn_congestion_threshold_read(struct file *file,
	145	char __user *buf, size_t len,
	146	loff_t *ppos)
	147	{
	148	struct fuse_conn *fc;
	149	unsigned val;
	150
	151	fc = fuse_ctl_file_conn_get(file);
	152	if (!fc)
	153	return 0;
	154
2a23f2b8	155	val = READ_ONCE(fc->congestion_threshold);
79a9d994 CH	156	fuse_conn_put(fc);
	157
	158	return fuse_conn_limit_read(file, buf, len, ppos, val);
	159	}
	160
	161	static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
	162	const char __user *buf,
	163	size_t count, loff_t *ppos)
	164	{
381bf7ca	165	unsigned uninitialized_var(val);
2b30a533	166	struct fuse_conn *fc;
79a9d994 CH	167	ssize_t ret;
	168
	169	ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
	170	max_user_congthresh);
2b30a533 KT	171	if (ret <= 0)
	172	goto out;
	173	fc = fuse_ctl_file_conn_get(file);
	174	if (!fc)
	175	goto out;
	176
ae2dffa3	177	spin_lock(&fc->bg_lock);
2b30a533 KT	178	fc->congestion_threshold = val;
	179	if (fc->sb) {
	180	if (fc->num_background < fc->congestion_threshold) {
	181	clear_bdi_congested(fc->sb->s_bdi, BLK_RW_SYNC);
	182	clear_bdi_congested(fc->sb->s_bdi, BLK_RW_ASYNC);
	183	} else {
	184	set_bdi_congested(fc->sb->s_bdi, BLK_RW_SYNC);
	185	set_bdi_congested(fc->sb->s_bdi, BLK_RW_ASYNC);
79a9d994 CH	186	}
79a9d994 CH	187	}
ae2dffa3	188	spin_unlock(&fc->bg_lock);
2b30a533 KT	189	fuse_conn_put(fc);
2b30a533 KT	190	out:
79a9d994 CH	191	return ret;
	192	}
	193
bafa9654 MS	194	static const struct file_operations fuse_ctl_abort_ops = {
	195	.open = nonseekable_open,
	196	.write = fuse_conn_abort_write,
6038f373	197	.llseek = no_llseek,
bafa9654 MS	198	};
	199
	200	static const struct file_operations fuse_ctl_waiting_ops = {
	201	.open = nonseekable_open,
	202	.read = fuse_conn_waiting_read,
6038f373	203	.llseek = no_llseek,
bafa9654 MS	204	};
bafa9654 MS	205
79a9d994 CH	206	static const struct file_operations fuse_conn_max_background_ops = {
	207	.open = nonseekable_open,
	208	.read = fuse_conn_max_background_read,
	209	.write = fuse_conn_max_background_write,
6038f373	210	.llseek = no_llseek,
79a9d994 CH	211	};
	212
	213	static const struct file_operations fuse_conn_congestion_threshold_ops = {
	214	.open = nonseekable_open,
	215	.read = fuse_conn_congestion_threshold_read,
	216	.write = fuse_conn_congestion_threshold_write,
6038f373	217	.llseek = no_llseek,
79a9d994 CH	218	};
79a9d994 CH	219
bafa9654 MS	220	static struct dentry fuse_ctl_add_dentry(struct dentry parent,
	221	struct fuse_conn *fc,
	222	const char *name,
	223	int mode, int nlink,
754661f1	224	const struct inode_operations *iop,
bafa9654 MS	225	const struct file_operations *fop)
	226	{
	227	struct dentry *dentry;
	228	struct inode *inode;
	229
	230	BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
	231	dentry = d_alloc_name(parent, name);
	232	if (!dentry)
	233	return NULL;
	234
bafa9654	235	inode = new_inode(fuse_control_sb);
6becdb60 MS	236	if (!inode) {
6becdb60 MS	237	dput(dentry);
bafa9654	238	return NULL;
6becdb60	239	}
bafa9654	240
85fe4025	241	inode->i_ino = get_next_ino();
bafa9654 MS	242	inode->i_mode = mode;
	243	inode->i_uid = fc->user_id;
	244	inode->i_gid = fc->group_id;
078cd827	245	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
bafa9654 MS	246	/* setting ->i_op to NULL is not allowed */
	247	if (iop)
	248	inode->i_op = iop;
	249	inode->i_fop = fop;
bfe86848	250	set_nlink(inode, nlink);
8e18e294	251	inode->i_private = fc;
bafa9654	252	d_add(dentry, inode);
6becdb60 MS	253
	254	fc->ctl_dentry[fc->ctl_ndents++] = dentry;
	255
bafa9654 MS	256	return dentry;
	257	}
	258
	259	/*
	260	* Add a connection to the control filesystem (if it exists). Caller
873302c7	261	* must hold fuse_mutex
bafa9654 MS	262	*/
	263	int fuse_ctl_add_conn(struct fuse_conn *fc)
	264	{
	265	struct dentry *parent;
	266	char name[32];
	267
	268	if (!fuse_control_sb)
	269	return 0;
	270
	271	parent = fuse_control_sb->s_root;
2b0143b5	272	inc_nlink(d_inode(parent));
b6f2fcbc	273	sprintf(name, "%u", fc->dev);
bafa9654 MS	274	parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR \| 0500, 2,
	275	&simple_dir_inode_operations,
	276	&simple_dir_operations);
	277	if (!parent)
	278	goto err;
	279
	280	if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG \| 0400, 1,
79a9d994	281	NULL, &fuse_ctl_waiting_ops) \|\|
bafa9654	282	!fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG \| 0200, 1,
79a9d994 CH	283	NULL, &fuse_ctl_abort_ops) \|\|
	284	!fuse_ctl_add_dentry(parent, fc, "max_background", S_IFREG \| 0600,
	285	1, NULL, &fuse_conn_max_background_ops) \|\|
	286	!fuse_ctl_add_dentry(parent, fc, "congestion_threshold",
	287	S_IFREG \| 0600, 1, NULL,
	288	&fuse_conn_congestion_threshold_ops))
bafa9654 MS	289	goto err;
	290
	291	return 0;
	292
	293	err:
	294	fuse_ctl_remove_conn(fc);
	295	return -ENOMEM;
	296	}
	297
	298	/*
	299	* Remove a connection from the control filesystem (if it exists).
873302c7	300	* Caller must hold fuse_mutex
bafa9654 MS	301	*/
	302	void fuse_ctl_remove_conn(struct fuse_conn *fc)
	303	{
	304	int i;
	305
	306	if (!fuse_control_sb)
	307	return;
	308
	309	for (i = fc->ctl_ndents - 1; i >= 0; i--) {
	310	struct dentry *dentry = fc->ctl_dentry[i];
2b0143b5	311	d_inode(dentry)->i_private = NULL;
6becdb60 MS	312	if (!i) {
	313	/* Get rid of submounts: */
	314	d_invalidate(dentry);
	315	}
bafa9654 MS	316	dput(dentry);
bafa9654 MS	317	}
2b0143b5	318	drop_nlink(d_inode(fuse_control_sb->s_root));
bafa9654 MS	319	}
bafa9654 MS	320
29cc02d9	321	static int fuse_ctl_fill_super(struct super_block sb, struct fs_context fctx)
bafa9654	322	{
cda37124	323	static const struct tree_descr empty_descr = {""};
bafa9654 MS	324	struct fuse_conn *fc;
	325	int err;
	326
	327	err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
	328	if (err)
	329	return err;
	330
	331	mutex_lock(&fuse_mutex);
	332	BUG_ON(fuse_control_sb);
	333	fuse_control_sb = sb;
	334	list_for_each_entry(fc, &fuse_conn_list, entry) {
	335	err = fuse_ctl_add_conn(fc);
	336	if (err) {
	337	fuse_control_sb = NULL;
	338	mutex_unlock(&fuse_mutex);
	339	return err;
	340	}
	341	}
	342	mutex_unlock(&fuse_mutex);
	343
	344	return 0;
	345	}
	346
29cc02d9	347	static int fuse_ctl_get_tree(struct fs_context *fc)
bafa9654	348	{
c23a0bba	349	return get_tree_single(fc, fuse_ctl_fill_super);
29cc02d9 DH	350	}
	351
	352	static const struct fs_context_operations fuse_ctl_context_ops = {
	353	.get_tree = fuse_ctl_get_tree,
	354	};
	355
	356	static int fuse_ctl_init_fs_context(struct fs_context *fc)
	357	{
	358	fc->ops = &fuse_ctl_context_ops;
	359	return 0;
bafa9654 MS	360	}
	361
	362	static void fuse_ctl_kill_sb(struct super_block *sb)
	363	{
ff795447 MS	364	struct fuse_conn *fc;
ff795447 MS	365
bafa9654 MS	366	mutex_lock(&fuse_mutex);
bafa9654 MS	367	fuse_control_sb = NULL;
ff795447 MS	368	list_for_each_entry(fc, &fuse_conn_list, entry)
ff795447 MS	369	fc->ctl_ndents = 0;
bafa9654 MS	370	mutex_unlock(&fuse_mutex);
	371
	372	kill_litter_super(sb);
	373	}
	374
	375	static struct file_system_type fuse_ctl_fs_type = {
	376	.owner = THIS_MODULE,
	377	.name = "fusectl",
29cc02d9	378	.init_fs_context = fuse_ctl_init_fs_context,
bafa9654 MS	379	.kill_sb = fuse_ctl_kill_sb,
bafa9654 MS	380	};
7f78e035	381	MODULE_ALIAS_FS("fusectl");
bafa9654 MS	382
	383	int __init fuse_ctl_init(void)
	384	{
	385	return register_filesystem(&fuse_ctl_fs_type);
	386	}
	387
7736e8cc	388	void __exit fuse_ctl_cleanup(void)
bafa9654 MS	389	{
	390	unregister_filesystem(&fuse_ctl_fs_type);
	391	}