[net-next-2.6.git] / fs / notify / inotify / inotify_fsnotify.c

/*
 * fs/inotify_user.c - inotify support for userspace
 *
 * Authors:
 *	John McCutchan	<ttb@tentacle.dhs.org>
 *	Robert Love	<rml@novell.com>
 *
 * Copyright (C) 2005 John McCutchan
 * Copyright 2006 Hewlett-Packard Development Company, L.P.
 *
 * Copyright (C) 2009 Eric Paris <Red Hat Inc>
 * inotify was largely rewriten to make use of the fsnotify infrastructure
 *
 * 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> /* struct inode */
#include <linux/fsnotify_backend.h>
#include <linux/inotify.h>
#include <linux/path.h> /* struct path */
#include <linux/slab.h> /* kmem_* */
#include <linux/types.h>
#include <linux/sched.h>

#include "inotify.h"

/*
 * Check if 2 events contain the same information.  We do not compare private data
 * but at this moment that isn't a problem for any know fsnotify listeners.
 */
static bool event_compare(struct fsnotify_event *old, struct fsnotify_event *new)
{
	if ((old->mask == new->mask) &&
	    (old->to_tell == new->to_tell) &&
	    (old->data_type == new->data_type) &&
	    (old->name_len == new->name_len)) {
		switch (old->data_type) {
		case (FSNOTIFY_EVENT_INODE):
			/* remember, after old was put on the wait_q we aren't
			 * allowed to look at the inode any more, only thing
			 * left to check was if the file_name is the same */
			if (!old->name_len ||
			    !strcmp(old->file_name, new->file_name))
				return true;
			break;
		case (FSNOTIFY_EVENT_PATH):
			if ((old->path.mnt == new->path.mnt) &&
			    (old->path.dentry == new->path.dentry))
				return true;
			break;
		case (FSNOTIFY_EVENT_NONE):
			if (old->mask & FS_Q_OVERFLOW)
				return true;
			else if (old->mask & FS_IN_IGNORED)
				return false;
			return true;
		};
	}
	return false;
}

static int inotify_merge(struct list_head *list, struct fsnotify_event *event)
{
	struct fsnotify_event_holder *last_holder;
	struct fsnotify_event *last_event;
	int ret = 0;

	/* and the list better be locked by something too */
	spin_lock(&event->lock);

	last_holder = list_entry(list->prev, struct fsnotify_event_holder, event_list);
	last_event = last_holder->event;
	if (event_compare(last_event, event))
		ret = -EEXIST;

	spin_unlock(&event->lock);

	return ret;
}

static int inotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event)
{
	struct fsnotify_mark_entry *entry;
	struct inotify_inode_mark_entry *ientry;
	struct inode *to_tell;
	struct inotify_event_private_data *event_priv;
	struct fsnotify_event_private_data *fsn_event_priv;
	int wd, ret;

	to_tell = event->to_tell;

	spin_lock(&to_tell->i_lock);
	entry = fsnotify_find_mark_entry(group, to_tell);
	spin_unlock(&to_tell->i_lock);
	/* race with watch removal?  We already passes should_send */
	if (unlikely(!entry))
		return 0;
	ientry = container_of(entry, struct inotify_inode_mark_entry,
			      fsn_entry);
	wd = ientry->wd;

	event_priv = kmem_cache_alloc(event_priv_cachep, GFP_KERNEL);
	if (unlikely(!event_priv))
		return -ENOMEM;

	fsn_event_priv = &event_priv->fsnotify_event_priv_data;

	fsn_event_priv->group = group;
	event_priv->wd = wd;

	ret = fsnotify_add_notify_event(group, event, fsn_event_priv, inotify_merge);
	if (ret) {
		inotify_free_event_priv(fsn_event_priv);
		/* EEXIST says we tail matched, EOVERFLOW isn't something
		 * to report up the stack. */
		if ((ret == -EEXIST) ||
		    (ret == -EOVERFLOW))
			ret = 0;
	}

	/*
	 * If we hold the entry until after the event is on the queue
	 * IN_IGNORED won't be able to pass this event in the queue
	 */
	fsnotify_put_mark(entry);

	return ret;
}

static void inotify_freeing_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group)
{
	inotify_ignored_and_remove_idr(entry, group);
}

static bool inotify_should_send_event(struct fsnotify_group *group, struct inode *inode,
				      struct vfsmount *mnt, __u32 mask, void *data,
				      int data_type)
{
	struct fsnotify_mark_entry *entry;
	bool send;

	spin_lock(&inode->i_lock);
	entry = fsnotify_find_mark_entry(group, inode);
	spin_unlock(&inode->i_lock);
	if (!entry)
		return false;

	mask = (mask & ~FS_EVENT_ON_CHILD);
	send = (entry->mask & mask);

	/* find took a reference */
	fsnotify_put_mark(entry);

	return send;
}

/*
 * This is NEVER supposed to be called.  Inotify marks should either have been
 * removed from the idr when the watch was removed or in the
 * fsnotify_destroy_mark_by_group() call when the inotify instance was being
 * torn down.  This is only called if the idr is about to be freed but there
 * are still marks in it.
 */
static int idr_callback(int id, void *p, void *data)
{
	struct fsnotify_mark_entry *entry;
	struct inotify_inode_mark_entry *ientry;
	static bool warned = false;

	if (warned)
		return 0;

	warned = true;
	entry = p;
	ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);

	WARN(1, "inotify closing but id=%d for entry=%p in group=%p still in "
		"idr.  Probably leaking memory\n", id, p, data);

	/*
	 * I'm taking the liberty of assuming that the mark in question is a
	 * valid address and I'm dereferencing it.  This might help to figure
	 * out why we got here and the panic is no worse than the original
	 * BUG() that was here.
	 */
	if (entry)
		printk(KERN_WARNING "entry->group=%p inode=%p wd=%d\n",
			entry->group, entry->inode, ientry->wd);
	return 0;
}

static void inotify_free_group_priv(struct fsnotify_group *group)
{
	/* ideally the idr is empty and we won't hit the BUG in teh callback */
	idr_for_each(&group->inotify_data.idr, idr_callback, group);
	idr_remove_all(&group->inotify_data.idr);
	idr_destroy(&group->inotify_data.idr);
	free_uid(group->inotify_data.user);
}

void inotify_free_event_priv(struct fsnotify_event_private_data *fsn_event_priv)
{
	struct inotify_event_private_data *event_priv;


	event_priv = container_of(fsn_event_priv, struct inotify_event_private_data,
				  fsnotify_event_priv_data);

	kmem_cache_free(event_priv_cachep, event_priv);
}

const struct fsnotify_ops inotify_fsnotify_ops = {
	.handle_event = inotify_handle_event,
	.should_send_event = inotify_should_send_event,
	.free_group_priv = inotify_free_group_priv,
	.free_event_priv = inotify_free_event_priv,
	.freeing_mark = inotify_freeing_mark,
};
Commit	Line	Data
63c882a0 EP	1	/*
	2	* fs/inotify_user.c - inotify support for userspace
	3	*
	4	* Authors:
	5	* John McCutchan <ttb@tentacle.dhs.org>
	6	* Robert Love <rml@novell.com>
	7	*
	8	* Copyright (C) 2005 John McCutchan
	9	* Copyright 2006 Hewlett-Packard Development Company, L.P.
	10	*
	11	* Copyright (C) 2009 Eric Paris <Red Hat Inc>
	12	* inotify was largely rewriten to make use of the fsnotify infrastructure
	13	*
	14	* This program is free software; you can redistribute it and/or modify it
	15	* under the terms of the GNU General Public License as published by the
	16	* Free Software Foundation; either version 2, or (at your option) any
	17	* later version.
	18	*
	19	* This program is distributed in the hope that it will be useful, but
	20	* WITHOUT ANY WARRANTY; without even the implied warranty of
	21	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	22	* General Public License for more details.
	23	*/
	24
	25	#include <linux/fs.h> /* struct inode */
	26	#include <linux/fsnotify_backend.h>
	27	#include <linux/inotify.h>
	28	#include <linux/path.h> /* struct path */
	29	#include <linux/slab.h> /* kmem_* */
	30	#include <linux/types.h>
b3b38d84	31	#include <linux/sched.h>
63c882a0 EP	32
	33	#include "inotify.h"
	34
74766bbf EP	35	/*
	36	* Check if 2 events contain the same information. We do not compare private data
	37	* but at this moment that isn't a problem for any know fsnotify listeners.
	38	*/
	39	static bool event_compare(struct fsnotify_event old, struct fsnotify_event new)
	40	{
	41	if ((old->mask == new->mask) &&
	42	(old->to_tell == new->to_tell) &&
	43	(old->data_type == new->data_type) &&
	44	(old->name_len == new->name_len)) {
	45	switch (old->data_type) {
	46	case (FSNOTIFY_EVENT_INODE):
	47	/* remember, after old was put on the wait_q we aren't
	48	* allowed to look at the inode any more, only thing
	49	* left to check was if the file_name is the same */
	50	if (!old->name_len \|\|
	51	!strcmp(old->file_name, new->file_name))
	52	return true;
	53	break;
	54	case (FSNOTIFY_EVENT_PATH):
	55	if ((old->path.mnt == new->path.mnt) &&
	56	(old->path.dentry == new->path.dentry))
	57	return true;
	58	break;
	59	case (FSNOTIFY_EVENT_NONE):
	60	if (old->mask & FS_Q_OVERFLOW)
	61	return true;
	62	else if (old->mask & FS_IN_IGNORED)
	63	return false;
	64	return true;
	65	};
	66	}
	67	return false;
	68	}
	69
	70	static int inotify_merge(struct list_head list, struct fsnotify_event event)
	71	{
	72	struct fsnotify_event_holder *last_holder;
	73	struct fsnotify_event *last_event;
	74	int ret = 0;
	75
	76	/* and the list better be locked by something too */
	77	spin_lock(&event->lock);
	78
	79	last_holder = list_entry(list->prev, struct fsnotify_event_holder, event_list);
	80	last_event = last_holder->event;
	81	if (event_compare(last_event, event))
	82	ret = -EEXIST;
	83
	84	spin_unlock(&event->lock);
	85
	86	return ret;
	87	}
	88
63c882a0 EP	89	static int inotify_handle_event(struct fsnotify_group group, struct fsnotify_event event)
	90	{
	91	struct fsnotify_mark_entry *entry;
	92	struct inotify_inode_mark_entry *ientry;
	93	struct inode *to_tell;
	94	struct inotify_event_private_data *event_priv;
	95	struct fsnotify_event_private_data *fsn_event_priv;
	96	int wd, ret;
	97
	98	to_tell = event->to_tell;
	99
	100	spin_lock(&to_tell->i_lock);
	101	entry = fsnotify_find_mark_entry(group, to_tell);
	102	spin_unlock(&to_tell->i_lock);
	103	/* race with watch removal? We already passes should_send */
	104	if (unlikely(!entry))
	105	return 0;
	106	ientry = container_of(entry, struct inotify_inode_mark_entry,
	107	fsn_entry);
	108	wd = ientry->wd;
	109
	110	event_priv = kmem_cache_alloc(event_priv_cachep, GFP_KERNEL);
	111	if (unlikely(!event_priv))
	112	return -ENOMEM;
	113
	114	fsn_event_priv = &event_priv->fsnotify_event_priv_data;
	115
	116	fsn_event_priv->group = group;
	117	event_priv->wd = wd;
	118
74766bbf	119	ret = fsnotify_add_notify_event(group, event, fsn_event_priv, inotify_merge);
eef3a116	120	if (ret) {
63c882a0	121	inotify_free_event_priv(fsn_event_priv);
eef3a116 EP	122	/* EEXIST says we tail matched, EOVERFLOW isn't something
	123	* to report up the stack. */
	124	if ((ret == -EEXIST) \|\|
	125	(ret == -EOVERFLOW))
	126	ret = 0;
	127	}
63c882a0 EP	128
	129	/*
	130	* If we hold the entry until after the event is on the queue
	131	* IN_IGNORED won't be able to pass this event in the queue
	132	*/
	133	fsnotify_put_mark(entry);
	134
	135	return ret;
	136	}
	137
	138	static void inotify_freeing_mark(struct fsnotify_mark_entry entry, struct fsnotify_group group)
	139	{
528da3e9	140	inotify_ignored_and_remove_idr(entry, group);
63c882a0 EP	141	}
63c882a0 EP	142
7b0a04fb	143	static bool inotify_should_send_event(struct fsnotify_group group, struct inode inode,
3a9fb89f EP	144	struct vfsmount mnt, __u32 mask, void data,
3a9fb89f EP	145	int data_type)
63c882a0 EP	146	{
	147	struct fsnotify_mark_entry *entry;
	148	bool send;
	149
	150	spin_lock(&inode->i_lock);
	151	entry = fsnotify_find_mark_entry(group, inode);
	152	spin_unlock(&inode->i_lock);
	153	if (!entry)
	154	return false;
	155
e42e2773	156	mask = (mask & ~FS_EVENT_ON_CHILD);
63c882a0 EP	157	send = (entry->mask & mask);
	158
	159	/* find took a reference */
	160	fsnotify_put_mark(entry);
	161
	162	return send;
	163	}
	164
cf437426 EP	165	/*
	166	* This is NEVER supposed to be called. Inotify marks should either have been
	167	* removed from the idr when the watch was removed or in the
	168	* fsnotify_destroy_mark_by_group() call when the inotify instance was being
	169	* torn down. This is only called if the idr is about to be freed but there
	170	* are still marks in it.
	171	*/
63c882a0 EP	172	static int idr_callback(int id, void p, void data)
63c882a0 EP	173	{
cf437426 EP	174	struct fsnotify_mark_entry *entry;
	175	struct inotify_inode_mark_entry *ientry;
	176	static bool warned = false;
	177
	178	if (warned)
	179	return 0;
	180
976ae32b	181	warned = true;
cf437426 EP	182	entry = p;
	183	ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
	184
	185	WARN(1, "inotify closing but id=%d for entry=%p in group=%p still in "
	186	"idr. Probably leaking memory\n", id, p, data);
	187
	188	/*
	189	* I'm taking the liberty of assuming that the mark in question is a
	190	* valid address and I'm dereferencing it. This might help to figure
	191	* out why we got here and the panic is no worse than the original
	192	* BUG() that was here.
	193	*/
	194	if (entry)
	195	printk(KERN_WARNING "entry->group=%p inode=%p wd=%d\n",
	196	entry->group, entry->inode, ientry->wd);
63c882a0 EP	197	return 0;
	198	}
	199
	200	static void inotify_free_group_priv(struct fsnotify_group *group)
	201	{
	202	/* ideally the idr is empty and we won't hit the BUG in teh callback */
cf437426	203	idr_for_each(&group->inotify_data.idr, idr_callback, group);
63c882a0 EP	204	idr_remove_all(&group->inotify_data.idr);
63c882a0 EP	205	idr_destroy(&group->inotify_data.idr);
b3b38d84	206	free_uid(group->inotify_data.user);
63c882a0 EP	207	}
	208
	209	void inotify_free_event_priv(struct fsnotify_event_private_data *fsn_event_priv)
	210	{
	211	struct inotify_event_private_data *event_priv;
	212
	213
	214	event_priv = container_of(fsn_event_priv, struct inotify_event_private_data,
	215	fsnotify_event_priv_data);
	216
	217	kmem_cache_free(event_priv_cachep, event_priv);
	218	}
	219
	220	const struct fsnotify_ops inotify_fsnotify_ops = {
	221	.handle_event = inotify_handle_event,
	222	.should_send_event = inotify_should_send_event,
	223	.free_group_priv = inotify_free_group_priv,
	224	.free_event_priv = inotify_free_event_priv,
	225	.freeing_mark = inotify_freeing_mark,
	226	};