[linux.git] / fs / dnotify.c

/*
 * Directory notifications for Linux.
 *
 * Copyright (C) 2000,2001,2002 Stephen Rothwell
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 */
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/dnotify.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/slab.h>

int dir_notify_enable = 1;

static kmem_cache_t *dn_cache;

static void redo_inode_mask(struct inode *inode)
{
	unsigned long new_mask;
	struct dnotify_struct *dn;

	new_mask = 0;
	for (dn = inode->i_dnotify; dn != NULL; dn = dn->dn_next)
		new_mask |= dn->dn_mask & ~DN_MULTISHOT;
	inode->i_dnotify_mask = new_mask;
}

void dnotify_flush(struct file *filp, fl_owner_t id)
{
	struct dnotify_struct *dn;
	struct dnotify_struct **prev;
	struct inode *inode;

	inode = filp->f_dentry->d_inode;
	if (!S_ISDIR(inode->i_mode))
		return;
	spin_lock(&inode->i_lock);
	prev = &inode->i_dnotify;
	while ((dn = *prev) != NULL) {
		if ((dn->dn_owner == id) && (dn->dn_filp == filp)) {
			*prev = dn->dn_next;
			redo_inode_mask(inode);
			kmem_cache_free(dn_cache, dn);
			break;
		}
		prev = &dn->dn_next;
	}
	spin_unlock(&inode->i_lock);
}

int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
{
	struct dnotify_struct *dn;
	struct dnotify_struct *odn;
	struct dnotify_struct **prev;
	struct inode *inode;
	fl_owner_t id = current->files;
	int error = 0;

	if ((arg & ~DN_MULTISHOT) == 0) {
		dnotify_flush(filp, id);
		return 0;
	}
	if (!dir_notify_enable)
		return -EINVAL;
	inode = filp->f_dentry->d_inode;
	if (!S_ISDIR(inode->i_mode))
		return -ENOTDIR;
	dn = kmem_cache_alloc(dn_cache, SLAB_KERNEL);
	if (dn == NULL)
		return -ENOMEM;
	spin_lock(&inode->i_lock);
	prev = &inode->i_dnotify;
	while ((odn = *prev) != NULL) {
		if ((odn->dn_owner == id) && (odn->dn_filp == filp)) {
			odn->dn_fd = fd;
			odn->dn_mask |= arg;
			inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
			goto out_free;
		}
		prev = &odn->dn_next;
	}

	error = f_setown(filp, current->pid, 0);
	if (error)
		goto out_free;

	dn->dn_mask = arg;
	dn->dn_fd = fd;
	dn->dn_filp = filp;
	dn->dn_owner = id;
	inode->i_dnotify_mask |= arg & ~DN_MULTISHOT;
	dn->dn_next = inode->i_dnotify;
	inode->i_dnotify = dn;
	spin_unlock(&inode->i_lock);

	if (filp->f_op && filp->f_op->dir_notify)
		return filp->f_op->dir_notify(filp, arg);
	return 0;

out_free:
	spin_unlock(&inode->i_lock);
	kmem_cache_free(dn_cache, dn);
	return error;
}

void __inode_dir_notify(struct inode *inode, unsigned long event)
{
	struct dnotify_struct *	dn;
	struct dnotify_struct **prev;
	struct fown_struct *	fown;
	int			changed = 0;

	spin_lock(&inode->i_lock);
	prev = &inode->i_dnotify;
	while ((dn = *prev) != NULL) {
		if ((dn->dn_mask & event) == 0) {
			prev = &dn->dn_next;
			continue;
		}
		fown = &dn->dn_filp->f_owner;
		send_sigio(fown, dn->dn_fd, POLL_MSG);
		if (dn->dn_mask & DN_MULTISHOT)
			prev = &dn->dn_next;
		else {
			*prev = dn->dn_next;
			changed = 1;
			kmem_cache_free(dn_cache, dn);
		}
	}
	if (changed)
		redo_inode_mask(inode);
	spin_unlock(&inode->i_lock);
}

EXPORT_SYMBOL(__inode_dir_notify);

/*
 * This is hopelessly wrong, but unfixable without API changes.  At
 * least it doesn't oops the kernel...
 *
 * To safely access ->d_parent we need to keep d_move away from it.  Use the
 * dentry's d_lock for this.
 */
void dnotify_parent(struct dentry *dentry, unsigned long event)
{
	struct dentry *parent;

	if (!dir_notify_enable)
		return;

	spin_lock(&dentry->d_lock);
	parent = dentry->d_parent;
	if (parent->d_inode->i_dnotify_mask & event) {
		dget(parent);
		spin_unlock(&dentry->d_lock);
		__inode_dir_notify(parent->d_inode, event);
		dput(parent);
	} else {
		spin_unlock(&dentry->d_lock);
	}
}
EXPORT_SYMBOL_GPL(dnotify_parent);

static int __init dnotify_init(void)
{
	dn_cache = kmem_cache_create("dnotify_cache",
		sizeof(struct dnotify_struct), 0, SLAB_PANIC, NULL, NULL);
	return 0;
}

module_init(dnotify_init)
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Directory notifications for Linux.
	3	*
	4	* Copyright (C) 2000,2001,2002 Stephen Rothwell
	5	*
	6	* This program is free software; you can redistribute it and/or modify it
	7	* under the terms of the GNU General Public License as published by the
	8	* Free Software Foundation; either version 2, or (at your option) any
	9	* later version.
	10	*
	11	* This program is distributed in the hope that it will be useful, but
	12	* WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	14	* General Public License for more details.
	15	*/
	16	#include <linux/fs.h>
	17	#include <linux/module.h>
	18	#include <linux/sched.h>
	19	#include <linux/dnotify.h>
	20	#include <linux/init.h>
	21	#include <linux/spinlock.h>
	22	#include <linux/slab.h>
	23
	24	int dir_notify_enable = 1;
	25
	26	static kmem_cache_t *dn_cache;
	27
	28	static void redo_inode_mask(struct inode *inode)
	29	{
	30	unsigned long new_mask;
	31	struct dnotify_struct *dn;
	32
	33	new_mask = 0;
	34	for (dn = inode->i_dnotify; dn != NULL; dn = dn->dn_next)
	35	new_mask \|= dn->dn_mask & ~DN_MULTISHOT;
	36	inode->i_dnotify_mask = new_mask;
	37	}
	38
	39	void dnotify_flush(struct file *filp, fl_owner_t id)
	40	{
	41	struct dnotify_struct *dn;
	42	struct dnotify_struct **prev;
	43	struct inode *inode;
	44
	45	inode = filp->f_dentry->d_inode;
	46	if (!S_ISDIR(inode->i_mode))
	47	return;
	48	spin_lock(&inode->i_lock);
	49	prev = &inode->i_dnotify;
	50	while ((dn = *prev) != NULL) {
	51	if ((dn->dn_owner == id) && (dn->dn_filp == filp)) {
	52	*prev = dn->dn_next;
	53	redo_inode_mask(inode);
	54	kmem_cache_free(dn_cache, dn);
	55	break;
	56	}
	57	prev = &dn->dn_next;
	58	}
	59	spin_unlock(&inode->i_lock);
	60	}
	61
	62	int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
	63	{
	64	struct dnotify_struct *dn;
65	struct dnotify_struct *odn;
66	struct dnotify_struct **prev;
67	struct inode *inode;
68	fl_owner_t id = current->files;
69	int error = 0;
70
71	if ((arg & ~DN_MULTISHOT) == 0) {
72	dnotify_flush(filp, id);
73	return 0;
74	}
75	if (!dir_notify_enable)
76	return -EINVAL;
77	inode = filp->f_dentry->d_inode;
78	if (!S_ISDIR(inode->i_mode))
79	return -ENOTDIR;
80	dn = kmem_cache_alloc(dn_cache, SLAB_KERNEL);
81	if (dn == NULL)
82	return -ENOMEM;
83	spin_lock(&inode->i_lock);
84	prev = &inode->i_dnotify;
85	while ((odn = *prev) != NULL) {
86	if ((odn->dn_owner == id) && (odn->dn_filp == filp)) {
87	odn->dn_fd = fd;
88	odn->dn_mask \|= arg;
89	inode->i_dnotify_mask \|= arg & ~DN_MULTISHOT;
90	goto out_free;
91	}
92	prev = &odn->dn_next;
93	}
94
95	error = f_setown(filp, current->pid, 0);
96	if (error)
97	goto out_free;
98
99	dn->dn_mask = arg;
100	dn->dn_fd = fd;
101	dn->dn_filp = filp;
102	dn->dn_owner = id;
103	inode->i_dnotify_mask \|= arg & ~DN_MULTISHOT;
104	dn->dn_next = inode->i_dnotify;
105	inode->i_dnotify = dn;
106	spin_unlock(&inode->i_lock);
107
108	if (filp->f_op && filp->f_op->dir_notify)
109	return filp->f_op->dir_notify(filp, arg);
110	return 0;
111
112	out_free:
113	spin_unlock(&inode->i_lock);
114	kmem_cache_free(dn_cache, dn);
115	return error;
116	}
117
118	void __inode_dir_notify(struct inode *inode, unsigned long event)
119	{
120	struct dnotify_struct * dn;
121	struct dnotify_struct **prev;
122	struct fown_struct * fown;
123	int changed = 0;
124
125	spin_lock(&inode->i_lock);
126	prev = &inode->i_dnotify;
127	while ((dn = *prev) != NULL) {
128	if ((dn->dn_mask & event) == 0) {
129	prev = &dn->dn_next;
130	continue;
131	}
132	fown = &dn->dn_filp->f_owner;
133	send_sigio(fown, dn->dn_fd, POLL_MSG);
134	if (dn->dn_mask & DN_MULTISHOT)
135	prev = &dn->dn_next;
136	else {
137	*prev = dn->dn_next;
138	changed = 1;
139	kmem_cache_free(dn_cache, dn);
140	}
141	}
142	if (changed)
143	redo_inode_mask(inode);
144	spin_unlock(&inode->i_lock);
145	}
146
147	EXPORT_SYMBOL(__inode_dir_notify);
148
149	/*
150	* This is hopelessly wrong, but unfixable without API changes. At
151	* least it doesn't oops the kernel...
152	*
153	* To safely access ->d_parent we need to keep d_move away from it. Use the
154	* dentry's d_lock for this.
155	*/
156	void dnotify_parent(struct dentry *dentry, unsigned long event)
157	{
158	struct dentry *parent;
159
160	if (!dir_notify_enable)
161	return;
162
163	spin_lock(&dentry->d_lock);
164	parent = dentry->d_parent;
165	if (parent->d_inode->i_dnotify_mask & event) {
166	dget(parent);
167	spin_unlock(&dentry->d_lock);
168	__inode_dir_notify(parent->d_inode, event);
169	dput(parent);
170	} else {
171	spin_unlock(&dentry->d_lock);
172	}
173	}
174	EXPORT_SYMBOL_GPL(dnotify_parent);
175
176	static int __init dnotify_init(void)
177	{
178	dn_cache = kmem_cache_create("dnotify_cache",
179	sizeof(struct dnotify_struct), 0, SLAB_PANIC, NULL, NULL);
180	return 0;
181	}
182
183	module_init(dnotify_init)