[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->f_path.dentry->d_inode->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;
	char tmp[32];
	unsigned limit = (1 << 16) - 1;
	int err;

	if (*ppos || count >= sizeof(tmp) - 1)
		return -EINVAL;

	if (copy_from_user(tmp, buf, count))
		return -EINVAL;

	tmp[count] = '\0';

	err = strict_strtoul(tmp, 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 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 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;
	/* 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(parent->d_inode);
	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];
		dentry->d_inode->i_private = NULL;
		d_drop(dentry);
		dput(dentry);
	}
	drop_nlink(fuse_control_sb->s_root->d_inode);
}

static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent)
{
	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,
};

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

void 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);
7706a9d6	26	fc = file->f_path.dentry->d_inode->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;
	78	char tmp[32];
	79	unsigned limit = (1 << 16) - 1;
	80	int err;
	81
	82	if (*ppos \|\| count >= sizeof(tmp) - 1)
	83	return -EINVAL;
	84
	85	if (copy_from_user(tmp, buf, count))
	86	return -EINVAL;
	87
	88	tmp[count] = '\0';
	89
	90	err = strict_strtoul(tmp, 0, &t);
	91	if (err)
	92	return err;
	93
	94	if (!capable(CAP_SYS_ADMIN))
	95	limit = min(limit, global_limit);
	96
	97	if (t > limit)
	98	return -EINVAL;
	99
	100	*val = t;
	101
	102	return count;
	103	}
	104
	105	static ssize_t fuse_conn_max_background_read(struct file *file,
	106	char __user *buf, size_t len,
	107	loff_t *ppos)
	108	{
	109	struct fuse_conn *fc;
	110	unsigned val;
	111
	112	fc = fuse_ctl_file_conn_get(file);
	113	if (!fc)
	114	return 0;
	115
	116	val = fc->max_background;
	117	fuse_conn_put(fc);
	118
	119	return fuse_conn_limit_read(file, buf, len, ppos, val);
	120	}
	121
	122	static ssize_t fuse_conn_max_background_write(struct file *file,
	123	const char __user *buf,
	124	size_t count, loff_t *ppos)
	125	{
	126	unsigned val;
	127	ssize_t ret;
128
129	ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
130	max_user_bgreq);
131	if (ret > 0) {
132	struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
133	if (fc) {
134	fc->max_background = val;
135	fuse_conn_put(fc);
136	}
137	}
138
139	return ret;
140	}
141
142	static ssize_t fuse_conn_congestion_threshold_read(struct file *file,
143	char __user *buf, size_t len,
144	loff_t *ppos)
145	{
146	struct fuse_conn *fc;
147	unsigned val;
148
149	fc = fuse_ctl_file_conn_get(file);
150	if (!fc)
151	return 0;
152
153	val = fc->congestion_threshold;
154	fuse_conn_put(fc);
155
156	return fuse_conn_limit_read(file, buf, len, ppos, val);
157	}
158
159	static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
160	const char __user *buf,
161	size_t count, loff_t *ppos)
162	{
163	unsigned val;
164	ssize_t ret;
165
166	ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
167	max_user_congthresh);
168	if (ret > 0) {
169	struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
170	if (fc) {
171	fc->congestion_threshold = val;
172	fuse_conn_put(fc);
173	}
174	}
175
176	return ret;
177	}
178
bafa9654 MS	179	static const struct file_operations fuse_ctl_abort_ops = {
	180	.open = nonseekable_open,
	181	.write = fuse_conn_abort_write,
6038f373	182	.llseek = no_llseek,
bafa9654 MS	183	};
	184
	185	static const struct file_operations fuse_ctl_waiting_ops = {
	186	.open = nonseekable_open,
	187	.read = fuse_conn_waiting_read,
6038f373	188	.llseek = no_llseek,
bafa9654 MS	189	};
bafa9654 MS	190
79a9d994 CH	191	static const struct file_operations fuse_conn_max_background_ops = {
	192	.open = nonseekable_open,
	193	.read = fuse_conn_max_background_read,
	194	.write = fuse_conn_max_background_write,
6038f373	195	.llseek = no_llseek,
79a9d994 CH	196	};
	197
	198	static const struct file_operations fuse_conn_congestion_threshold_ops = {
	199	.open = nonseekable_open,
	200	.read = fuse_conn_congestion_threshold_read,
	201	.write = fuse_conn_congestion_threshold_write,
6038f373	202	.llseek = no_llseek,
79a9d994 CH	203	};
79a9d994 CH	204
bafa9654 MS	205	static struct dentry fuse_ctl_add_dentry(struct dentry parent,
	206	struct fuse_conn *fc,
	207	const char *name,
	208	int mode, int nlink,
754661f1	209	const struct inode_operations *iop,
bafa9654 MS	210	const struct file_operations *fop)
	211	{
	212	struct dentry *dentry;
	213	struct inode *inode;
	214
	215	BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
	216	dentry = d_alloc_name(parent, name);
	217	if (!dentry)
	218	return NULL;
	219
	220	fc->ctl_dentry[fc->ctl_ndents++] = dentry;
	221	inode = new_inode(fuse_control_sb);
	222	if (!inode)
	223	return NULL;
	224
85fe4025	225	inode->i_ino = get_next_ino();
bafa9654 MS	226	inode->i_mode = mode;
	227	inode->i_uid = fc->user_id;
	228	inode->i_gid = fc->group_id;
	229	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	230	/* setting ->i_op to NULL is not allowed */
	231	if (iop)
	232	inode->i_op = iop;
	233	inode->i_fop = fop;
bfe86848	234	set_nlink(inode, nlink);
8e18e294	235	inode->i_private = fc;
bafa9654 MS	236	d_add(dentry, inode);
	237	return dentry;
	238	}
	239
	240	/*
	241	* Add a connection to the control filesystem (if it exists). Caller
873302c7	242	* must hold fuse_mutex
bafa9654 MS	243	*/
	244	int fuse_ctl_add_conn(struct fuse_conn *fc)
	245	{
	246	struct dentry *parent;
	247	char name[32];
	248
	249	if (!fuse_control_sb)
	250	return 0;
	251
	252	parent = fuse_control_sb->s_root;
d8c76e6f	253	inc_nlink(parent->d_inode);
b6f2fcbc	254	sprintf(name, "%u", fc->dev);
bafa9654 MS	255	parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR \| 0500, 2,
	256	&simple_dir_inode_operations,
	257	&simple_dir_operations);
	258	if (!parent)
	259	goto err;
	260
	261	if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG \| 0400, 1,
79a9d994	262	NULL, &fuse_ctl_waiting_ops) \|\|
bafa9654	263	!fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG \| 0200, 1,
79a9d994 CH	264	NULL, &fuse_ctl_abort_ops) \|\|
	265	!fuse_ctl_add_dentry(parent, fc, "max_background", S_IFREG \| 0600,
	266	1, NULL, &fuse_conn_max_background_ops) \|\|
	267	!fuse_ctl_add_dentry(parent, fc, "congestion_threshold",
	268	S_IFREG \| 0600, 1, NULL,
	269	&fuse_conn_congestion_threshold_ops))
bafa9654 MS	270	goto err;
	271
	272	return 0;
	273
	274	err:
	275	fuse_ctl_remove_conn(fc);
	276	return -ENOMEM;
	277	}
	278
	279	/*
	280	* Remove a connection from the control filesystem (if it exists).
873302c7	281	* Caller must hold fuse_mutex
bafa9654 MS	282	*/
	283	void fuse_ctl_remove_conn(struct fuse_conn *fc)
	284	{
	285	int i;
	286
	287	if (!fuse_control_sb)
	288	return;
	289
	290	for (i = fc->ctl_ndents - 1; i >= 0; i--) {
	291	struct dentry *dentry = fc->ctl_dentry[i];
8e18e294	292	dentry->d_inode->i_private = NULL;
bafa9654 MS	293	d_drop(dentry);
	294	dput(dentry);
	295	}
d6db07de	296	drop_nlink(fuse_control_sb->s_root->d_inode);
bafa9654 MS	297	}
	298
	299	static int fuse_ctl_fill_super(struct super_block sb, void data, int silent)
	300	{
	301	struct tree_descr empty_descr = {""};
	302	struct fuse_conn *fc;
	303	int err;
	304
	305	err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
	306	if (err)
	307	return err;
	308
	309	mutex_lock(&fuse_mutex);
	310	BUG_ON(fuse_control_sb);
	311	fuse_control_sb = sb;
	312	list_for_each_entry(fc, &fuse_conn_list, entry) {
	313	err = fuse_ctl_add_conn(fc);
	314	if (err) {
	315	fuse_control_sb = NULL;
	316	mutex_unlock(&fuse_mutex);
	317	return err;
	318	}
	319	}
	320	mutex_unlock(&fuse_mutex);
	321
	322	return 0;
	323	}
	324
fc14f2fe AV	325	static struct dentry fuse_ctl_mount(struct file_system_type fs_type,
fc14f2fe AV	326	int flags, const char dev_name, void raw_data)
bafa9654	327	{
fc14f2fe	328	return mount_single(fs_type, flags, raw_data, fuse_ctl_fill_super);
bafa9654 MS	329	}
	330
	331	static void fuse_ctl_kill_sb(struct super_block *sb)
	332	{
ff795447 MS	333	struct fuse_conn *fc;
ff795447 MS	334
bafa9654 MS	335	mutex_lock(&fuse_mutex);
bafa9654 MS	336	fuse_control_sb = NULL;
ff795447 MS	337	list_for_each_entry(fc, &fuse_conn_list, entry)
ff795447 MS	338	fc->ctl_ndents = 0;
bafa9654 MS	339	mutex_unlock(&fuse_mutex);
	340
	341	kill_litter_super(sb);
	342	}
	343
	344	static struct file_system_type fuse_ctl_fs_type = {
	345	.owner = THIS_MODULE,
	346	.name = "fusectl",
fc14f2fe	347	.mount = fuse_ctl_mount,
bafa9654 MS	348	.kill_sb = fuse_ctl_kill_sb,
	349	};
	350
	351	int __init fuse_ctl_init(void)
	352	{
	353	return register_filesystem(&fuse_ctl_fs_type);
	354	}
	355
	356	void fuse_ctl_cleanup(void)
	357	{
	358	unregister_filesystem(&fuse_ctl_fs_type);
	359	}