[deliverable/linux.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>

#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 const struct file_operations fuse_ctl_abort_ops = {
	.open = nonseekable_open,
	.write = fuse_conn_abort_write,
};

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

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_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;
	inode->i_nlink = 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))
		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);
	}
	fuse_control_sb->s_root->d_inode->i_nlink--;
}

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 int fuse_ctl_get_sb(struct file_system_type *fs_type, int flags,
			const char *dev_name, void *raw_data,
			struct vfsmount *mnt)
{
	return get_sb_single(fs_type, flags, raw_data,
				fuse_ctl_fill_super, mnt);
}

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",
	.get_sb		= fuse_ctl_get_sb,
	.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 <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>
	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
	64	static const struct file_operations fuse_ctl_abort_ops = {
	65	.open = nonseekable_open,
	66	.write = fuse_conn_abort_write,
	67	};
	68
	69	static const struct file_operations fuse_ctl_waiting_ops = {
	70	.open = nonseekable_open,
	71	.read = fuse_conn_waiting_read,
	72	};
	73
	74	static struct dentry fuse_ctl_add_dentry(struct dentry parent,
	75	struct fuse_conn *fc,
	76	const char *name,
	77	int mode, int nlink,
754661f1	78	const struct inode_operations *iop,
bafa9654 MS	79	const struct file_operations *fop)
	80	{
	81	struct dentry *dentry;
	82	struct inode *inode;
	83
	84	BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
	85	dentry = d_alloc_name(parent, name);
	86	if (!dentry)
	87	return NULL;
	88
	89	fc->ctl_dentry[fc->ctl_ndents++] = dentry;
	90	inode = new_inode(fuse_control_sb);
	91	if (!inode)
	92	return NULL;
	93
	94	inode->i_mode = mode;
	95	inode->i_uid = fc->user_id;
	96	inode->i_gid = fc->group_id;
	97	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	98	/* setting ->i_op to NULL is not allowed */
	99	if (iop)
	100	inode->i_op = iop;
	101	inode->i_fop = fop;
	102	inode->i_nlink = nlink;
8e18e294	103	inode->i_private = fc;
bafa9654 MS	104	d_add(dentry, inode);
	105	return dentry;
	106	}
	107
	108	/*
	109	* Add a connection to the control filesystem (if it exists). Caller
873302c7	110	* must hold fuse_mutex
bafa9654 MS	111	*/
	112	int fuse_ctl_add_conn(struct fuse_conn *fc)
	113	{
	114	struct dentry *parent;
	115	char name[32];
	116
	117	if (!fuse_control_sb)
	118	return 0;
	119
	120	parent = fuse_control_sb->s_root;
d8c76e6f	121	inc_nlink(parent->d_inode);
b6f2fcbc	122	sprintf(name, "%u", fc->dev);
bafa9654 MS	123	parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR \| 0500, 2,
	124	&simple_dir_inode_operations,
	125	&simple_dir_operations);
	126	if (!parent)
	127	goto err;
	128
	129	if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG \| 0400, 1,
	130	NULL, &fuse_ctl_waiting_ops) \|\|
	131	!fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG \| 0200, 1,
	132	NULL, &fuse_ctl_abort_ops))
	133	goto err;
	134
	135	return 0;
	136
	137	err:
	138	fuse_ctl_remove_conn(fc);
	139	return -ENOMEM;
	140	}
	141
	142	/*
	143	* Remove a connection from the control filesystem (if it exists).
873302c7	144	* Caller must hold fuse_mutex
bafa9654 MS	145	*/
	146	void fuse_ctl_remove_conn(struct fuse_conn *fc)
	147	{
	148	int i;
	149
	150	if (!fuse_control_sb)
	151	return;
	152
	153	for (i = fc->ctl_ndents - 1; i >= 0; i--) {
	154	struct dentry *dentry = fc->ctl_dentry[i];
8e18e294	155	dentry->d_inode->i_private = NULL;
bafa9654 MS	156	d_drop(dentry);
	157	dput(dentry);
	158	}
	159	fuse_control_sb->s_root->d_inode->i_nlink--;
	160	}
	161
	162	static int fuse_ctl_fill_super(struct super_block sb, void data, int silent)
	163	{
	164	struct tree_descr empty_descr = {""};
	165	struct fuse_conn *fc;
	166	int err;
	167
	168	err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
	169	if (err)
	170	return err;
	171
	172	mutex_lock(&fuse_mutex);
	173	BUG_ON(fuse_control_sb);
	174	fuse_control_sb = sb;
	175	list_for_each_entry(fc, &fuse_conn_list, entry) {
	176	err = fuse_ctl_add_conn(fc);
	177	if (err) {
	178	fuse_control_sb = NULL;
	179	mutex_unlock(&fuse_mutex);
	180	return err;
	181	}
	182	}
	183	mutex_unlock(&fuse_mutex);
	184
	185	return 0;
	186	}
	187
	188	static int fuse_ctl_get_sb(struct file_system_type *fs_type, int flags,
	189	const char dev_name, void raw_data,
	190	struct vfsmount *mnt)
	191	{
	192	return get_sb_single(fs_type, flags, raw_data,
	193	fuse_ctl_fill_super, mnt);
	194	}
	195
	196	static void fuse_ctl_kill_sb(struct super_block *sb)
	197	{
ff795447 MS	198	struct fuse_conn *fc;
ff795447 MS	199
bafa9654 MS	200	mutex_lock(&fuse_mutex);
bafa9654 MS	201	fuse_control_sb = NULL;
ff795447 MS	202	list_for_each_entry(fc, &fuse_conn_list, entry)
ff795447 MS	203	fc->ctl_ndents = 0;
bafa9654 MS	204	mutex_unlock(&fuse_mutex);
	205
	206	kill_litter_super(sb);
	207	}
	208
	209	static struct file_system_type fuse_ctl_fs_type = {
	210	.owner = THIS_MODULE,
	211	.name = "fusectl",
	212	.get_sb = fuse_ctl_get_sb,
	213	.kill_sb = fuse_ctl_kill_sb,
	214	};
	215
	216	int __init fuse_ctl_init(void)
	217	{
	218	return register_filesystem(&fuse_ctl_fs_type);
	219	}
	220
	221	void fuse_ctl_cleanup(void)
	222	{
	223	unregister_filesystem(&fuse_ctl_fs_type);
	224	}