[linux.git] / fs / fuse / control.c

/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2008  Miklos Szeredi <[email protected]>

  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>

#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) {
		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 = 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) {
			fc->max_background = val;
			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 = 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);
	ssize_t ret;

	ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
				    max_user_congthresh);
	if (ret > 0) {
		struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
		if (fc) {
			fc->congestion_threshold = val;
			fuse_conn_put(fc);
		}
	}

	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;

	fc->ctl_dentry[fc->ctl_ndents++] = dentry;
	inode = new_inode(fuse_control_sb);
	if (!inode)
		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);
	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;
		d_drop(dentry);
		dput(dentry);
	}
	drop_nlink(d_inode(fuse_control_sb->s_root));
}

static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent)
{
	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 struct dentry *fuse_ctl_mount(struct file_system_type *fs_type,
			int flags, const char *dev_name, void *raw_data)
{
	return mount_single(fs_type, flags, raw_data, fuse_ctl_fill_super);
}

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",
	.mount		= fuse_ctl_mount,
	.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 <[email protected]>
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>
	13
	14	#define FUSE_CTL_SUPER_MAGIC 0x65735543
	15
	16	/*
	17	* This is non-NULL when the single instance of the control filesystem
	18	* exists. Protected by fuse_mutex
	19	*/
	20	static struct super_block *fuse_control_sb;
	21
	22	static struct fuse_conn fuse_ctl_file_conn_get(struct file file)
	23	{
	24	struct fuse_conn *fc;
	25	mutex_lock(&fuse_mutex);
496ad9aa	26	fc = file_inode(file)->i_private;
bafa9654 MS	27	if (fc)
	28	fc = fuse_conn_get(fc);
	29	mutex_unlock(&fuse_mutex);
	30	return fc;
	31	}
	32
	33	static ssize_t fuse_conn_abort_write(struct file file, const char __user buf,
	34	size_t count, loff_t *ppos)
	35	{
	36	struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
	37	if (fc) {
	38	fuse_abort_conn(fc);
	39	fuse_conn_put(fc);
	40	}
	41	return count;
	42	}
	43
	44	static ssize_t fuse_conn_waiting_read(struct file file, char __user buf,
	45	size_t len, loff_t *ppos)
	46	{
	47	char tmp[32];
	48	size_t size;
	49
	50	if (!*ppos) {
1729a16c	51	long value;
bafa9654 MS	52	struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
	53	if (!fc)
	54	return 0;
	55
1729a16c MS	56	value = atomic_read(&fc->num_waiting);
1729a16c MS	57	file->private_data = (void *)value;
bafa9654 MS	58	fuse_conn_put(fc);
	59	}
	60	size = sprintf(tmp, "%ld\n", (long)file->private_data);
	61	return simple_read_from_buffer(buf, len, ppos, tmp, size);
	62	}
	63
79a9d994 CH	64	static ssize_t fuse_conn_limit_read(struct file file, char __user buf,
	65	size_t len, loff_t *ppos, unsigned val)
	66	{
	67	char tmp[32];
	68	size_t size = sprintf(tmp, "%u\n", val);
	69
	70	return simple_read_from_buffer(buf, len, ppos, tmp, size);
	71	}
	72
	73	static ssize_t fuse_conn_limit_write(struct file file, const char __user buf,
	74	size_t count, loff_t ppos, unsigned val,
	75	unsigned global_limit)
	76	{
	77	unsigned long t;
79a9d994 CH	78	unsigned limit = (1 << 16) - 1;
	79	int err;
	80
e2690695	81	if (*ppos)
79a9d994 CH	82	return -EINVAL;
79a9d994 CH	83
e2690695	84	err = kstrtoul_from_user(buf, count, 0, &t);
79a9d994 CH	85	if (err)
	86	return err;
	87
	88	if (!capable(CAP_SYS_ADMIN))
	89	limit = min(limit, global_limit);
	90
	91	if (t > limit)
	92	return -EINVAL;
	93
	94	*val = t;
	95
	96	return count;
	97	}
	98
	99	static ssize_t fuse_conn_max_background_read(struct file *file,
	100	char __user *buf, size_t len,
	101	loff_t *ppos)
	102	{
	103	struct fuse_conn *fc;
	104	unsigned val;
	105
	106	fc = fuse_ctl_file_conn_get(file);
	107	if (!fc)
	108	return 0;
	109
	110	val = fc->max_background;
	111	fuse_conn_put(fc);
	112
	113	return fuse_conn_limit_read(file, buf, len, ppos, val);
	114	}
	115
	116	static ssize_t fuse_conn_max_background_write(struct file *file,
	117	const char __user *buf,
	118	size_t count, loff_t *ppos)
	119	{
381bf7ca	120	unsigned uninitialized_var(val);
79a9d994 CH	121	ssize_t ret;
	122
	123	ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
	124	max_user_bgreq);
	125	if (ret > 0) {
	126	struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
	127	if (fc) {
	128	fc->max_background = val;
	129	fuse_conn_put(fc);
	130	}
	131	}
	132
	133	return ret;
	134	}
	135
	136	static ssize_t fuse_conn_congestion_threshold_read(struct file *file,
	137	char __user *buf, size_t len,
	138	loff_t *ppos)
	139	{
	140	struct fuse_conn *fc;
	141	unsigned val;
	142
	143	fc = fuse_ctl_file_conn_get(file);
	144	if (!fc)
	145	return 0;
	146
	147	val = fc->congestion_threshold;
	148	fuse_conn_put(fc);
	149
	150	return fuse_conn_limit_read(file, buf, len, ppos, val);
	151	}
	152
	153	static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
	154	const char __user *buf,
	155	size_t count, loff_t *ppos)
	156	{
381bf7ca	157	unsigned uninitialized_var(val);
79a9d994 CH	158	ssize_t ret;
	159
	160	ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
	161	max_user_congthresh);
	162	if (ret > 0) {
	163	struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
	164	if (fc) {
	165	fc->congestion_threshold = val;
	166	fuse_conn_put(fc);
	167	}
	168	}
	169
	170	return ret;
	171	}
	172
bafa9654 MS	173	static const struct file_operations fuse_ctl_abort_ops = {
	174	.open = nonseekable_open,
	175	.write = fuse_conn_abort_write,
6038f373	176	.llseek = no_llseek,
bafa9654 MS	177	};
	178
	179	static const struct file_operations fuse_ctl_waiting_ops = {
	180	.open = nonseekable_open,
	181	.read = fuse_conn_waiting_read,
6038f373	182	.llseek = no_llseek,
bafa9654 MS	183	};
bafa9654 MS	184
79a9d994 CH	185	static const struct file_operations fuse_conn_max_background_ops = {
	186	.open = nonseekable_open,
	187	.read = fuse_conn_max_background_read,
	188	.write = fuse_conn_max_background_write,
6038f373	189	.llseek = no_llseek,
79a9d994 CH	190	};
	191
	192	static const struct file_operations fuse_conn_congestion_threshold_ops = {
	193	.open = nonseekable_open,
	194	.read = fuse_conn_congestion_threshold_read,
	195	.write = fuse_conn_congestion_threshold_write,
6038f373	196	.llseek = no_llseek,
79a9d994 CH	197	};
79a9d994 CH	198
bafa9654 MS	199	static struct dentry fuse_ctl_add_dentry(struct dentry parent,
	200	struct fuse_conn *fc,
	201	const char *name,
	202	int mode, int nlink,
754661f1	203	const struct inode_operations *iop,
bafa9654 MS	204	const struct file_operations *fop)
	205	{
	206	struct dentry *dentry;
	207	struct inode *inode;
	208
	209	BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
	210	dentry = d_alloc_name(parent, name);
	211	if (!dentry)
	212	return NULL;
	213
	214	fc->ctl_dentry[fc->ctl_ndents++] = dentry;
	215	inode = new_inode(fuse_control_sb);
	216	if (!inode)
	217	return NULL;
	218
85fe4025	219	inode->i_ino = get_next_ino();
bafa9654 MS	220	inode->i_mode = mode;
	221	inode->i_uid = fc->user_id;
	222	inode->i_gid = fc->group_id;
078cd827	223	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
bafa9654 MS	224	/* setting ->i_op to NULL is not allowed */
	225	if (iop)
	226	inode->i_op = iop;
	227	inode->i_fop = fop;
bfe86848	228	set_nlink(inode, nlink);
8e18e294	229	inode->i_private = fc;
bafa9654 MS	230	d_add(dentry, inode);
	231	return dentry;
	232	}
	233
	234	/*
	235	* Add a connection to the control filesystem (if it exists). Caller
873302c7	236	* must hold fuse_mutex
bafa9654 MS	237	*/
	238	int fuse_ctl_add_conn(struct fuse_conn *fc)
	239	{
	240	struct dentry *parent;
	241	char name[32];
	242
	243	if (!fuse_control_sb)
	244	return 0;
	245
	246	parent = fuse_control_sb->s_root;
2b0143b5	247	inc_nlink(d_inode(parent));
b6f2fcbc	248	sprintf(name, "%u", fc->dev);
bafa9654 MS	249	parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR \| 0500, 2,
	250	&simple_dir_inode_operations,
	251	&simple_dir_operations);
	252	if (!parent)
	253	goto err;
	254
	255	if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG \| 0400, 1,
79a9d994	256	NULL, &fuse_ctl_waiting_ops) \|\|
bafa9654	257	!fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG \| 0200, 1,
79a9d994 CH	258	NULL, &fuse_ctl_abort_ops) \|\|
	259	!fuse_ctl_add_dentry(parent, fc, "max_background", S_IFREG \| 0600,
	260	1, NULL, &fuse_conn_max_background_ops) \|\|
	261	!fuse_ctl_add_dentry(parent, fc, "congestion_threshold",
	262	S_IFREG \| 0600, 1, NULL,
	263	&fuse_conn_congestion_threshold_ops))
bafa9654 MS	264	goto err;
	265
	266	return 0;
	267
	268	err:
	269	fuse_ctl_remove_conn(fc);
	270	return -ENOMEM;
	271	}
	272
	273	/*
	274	* Remove a connection from the control filesystem (if it exists).
873302c7	275	* Caller must hold fuse_mutex
bafa9654 MS	276	*/
	277	void fuse_ctl_remove_conn(struct fuse_conn *fc)
	278	{
	279	int i;
	280
	281	if (!fuse_control_sb)
	282	return;
	283
	284	for (i = fc->ctl_ndents - 1; i >= 0; i--) {
	285	struct dentry *dentry = fc->ctl_dentry[i];
2b0143b5	286	d_inode(dentry)->i_private = NULL;
bafa9654 MS	287	d_drop(dentry);
	288	dput(dentry);
	289	}
2b0143b5	290	drop_nlink(d_inode(fuse_control_sb->s_root));
bafa9654 MS	291	}
	292
	293	static int fuse_ctl_fill_super(struct super_block sb, void data, int silent)
	294	{
cda37124	295	static const struct tree_descr empty_descr = {""};
bafa9654 MS	296	struct fuse_conn *fc;
	297	int err;
	298
	299	err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
	300	if (err)
	301	return err;
	302
	303	mutex_lock(&fuse_mutex);
	304	BUG_ON(fuse_control_sb);
	305	fuse_control_sb = sb;
	306	list_for_each_entry(fc, &fuse_conn_list, entry) {
	307	err = fuse_ctl_add_conn(fc);
	308	if (err) {
	309	fuse_control_sb = NULL;
	310	mutex_unlock(&fuse_mutex);
	311	return err;
	312	}
	313	}
	314	mutex_unlock(&fuse_mutex);
	315
	316	return 0;
	317	}
	318
fc14f2fe AV	319	static struct dentry fuse_ctl_mount(struct file_system_type fs_type,
fc14f2fe AV	320	int flags, const char dev_name, void raw_data)
bafa9654	321	{
fc14f2fe	322	return mount_single(fs_type, flags, raw_data, fuse_ctl_fill_super);
bafa9654 MS	323	}
	324
	325	static void fuse_ctl_kill_sb(struct super_block *sb)
	326	{
ff795447 MS	327	struct fuse_conn *fc;
ff795447 MS	328
bafa9654 MS	329	mutex_lock(&fuse_mutex);
bafa9654 MS	330	fuse_control_sb = NULL;
ff795447 MS	331	list_for_each_entry(fc, &fuse_conn_list, entry)
ff795447 MS	332	fc->ctl_ndents = 0;
bafa9654 MS	333	mutex_unlock(&fuse_mutex);
	334
	335	kill_litter_super(sb);
	336	}
	337
	338	static struct file_system_type fuse_ctl_fs_type = {
	339	.owner = THIS_MODULE,
	340	.name = "fusectl",
fc14f2fe	341	.mount = fuse_ctl_mount,
bafa9654 MS	342	.kill_sb = fuse_ctl_kill_sb,
bafa9654 MS	343	};
7f78e035	344	MODULE_ALIAS_FS("fusectl");
bafa9654 MS	345
	346	int __init fuse_ctl_init(void)
	347	{
	348	return register_filesystem(&fuse_ctl_fs_type);
	349	}
	350
7736e8cc	351	void __exit fuse_ctl_cleanup(void)
bafa9654 MS	352	{
	353	unregister_filesystem(&fuse_ctl_fs_type);
	354	}