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

/*
 *  Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
 *
 *  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.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/dcache.h>
#include <linux/fs.h>
#include <linux/gfp.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/srcu.h>

#include <linux/fsnotify_backend.h>
#include "fsnotify.h"

/*
 * Clear all of the marks on an inode when it is being evicted from core
 */
void __fsnotify_inode_delete(struct inode *inode)
{
	fsnotify_clear_marks_by_inode(inode);
}
EXPORT_SYMBOL_GPL(__fsnotify_inode_delete);

void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
{
	fsnotify_clear_marks_by_mount(mnt);
}

/*
 * Given an inode, first check if we care what happens to our children.  Inotify
 * and dnotify both tell their parents about events.  If we care about any event
 * on a child we run all of our children and set a dentry flag saying that the
 * parent cares.  Thus when an event happens on a child it can quickly tell if
 * if there is a need to find a parent and send the event to the parent.
 */
void __fsnotify_update_child_dentry_flags(struct inode *inode)
{
	struct dentry *alias;
	int watched;

	if (!S_ISDIR(inode->i_mode))
		return;

	/* determine if the children should tell inode about their events */
	watched = fsnotify_inode_watches_children(inode);

	spin_lock(&dcache_lock);
	/* run all of the dentries associated with this inode.  Since this is a
	 * directory, there damn well better only be one item on this list */
	list_for_each_entry(alias, &inode->i_dentry, d_alias) {
		struct dentry *child;

		/* run all of the children of the original inode and fix their
		 * d_flags to indicate parental interest (their parent is the
		 * original inode) */
		list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
			if (!child->d_inode)
				continue;

			spin_lock(&child->d_lock);
			if (watched)
				child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
			else
				child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
			spin_unlock(&child->d_lock);
		}
	}
	spin_unlock(&dcache_lock);
}

/* Notify this dentry's parent about a child's events. */
void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
{
	struct dentry *parent;
	struct inode *p_inode;

	if (!dentry)
		dentry = path->dentry;

	if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
		return;

	parent = dget_parent(dentry);
	p_inode = parent->d_inode;

	if (unlikely(!fsnotify_inode_watches_children(p_inode)))
		__fsnotify_update_child_dentry_flags(p_inode);
	else if (p_inode->i_fsnotify_mask & mask) {
		/* we are notifying a parent so come up with the new mask which
		 * specifies these are events which came from a child. */
		mask |= FS_EVENT_ON_CHILD;

		if (path)
			fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
				 dentry->d_name.name, 0);
		else
			fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
				 dentry->d_name.name, 0);
	}

	dput(parent);
}
EXPORT_SYMBOL_GPL(__fsnotify_parent);

static int send_to_group(struct inode *to_tell, struct vfsmount *mnt,
			 struct fsnotify_mark *inode_mark,
			 struct fsnotify_mark *vfsmount_mark,
			 __u32 mask, void *data,
			 int data_is, u32 cookie,
			 const unsigned char *file_name,
			 struct fsnotify_event **event)
{
	struct fsnotify_group *group = NULL;
	__u32 inode_test_mask = 0;
	__u32 vfsmount_test_mask = 0;

	if (unlikely(!inode_mark && !vfsmount_mark)) {
		BUG();
		return 0;
	}

	/* clear ignored on inode modification */
	if (mask & FS_MODIFY) {
		if (inode_mark &&
		    !(inode_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
			inode_mark->ignored_mask = 0;
		if (vfsmount_mark &&
		    !(vfsmount_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
			vfsmount_mark->ignored_mask = 0;
	}

	/* does the inode mark tell us to do something? */
	if (inode_mark) {
		group = inode_mark->group;
		inode_test_mask = (mask & ~FS_EVENT_ON_CHILD);
		inode_test_mask &= inode_mark->mask;
		inode_test_mask &= ~inode_mark->ignored_mask;
	}

	/* does the vfsmount_mark tell us to do something? */
	if (vfsmount_mark) {
		vfsmount_test_mask = (mask & ~FS_EVENT_ON_CHILD);
		group = vfsmount_mark->group;
		vfsmount_test_mask &= vfsmount_mark->mask;
		vfsmount_test_mask &= ~vfsmount_mark->ignored_mask;
		if (inode_mark)
			vfsmount_test_mask &= ~inode_mark->ignored_mask;
	}

	pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x inode_mark=%p"
		 " inode_test_mask=%x vfsmount_mark=%p vfsmount_test_mask=%x"
		 " data=%p data_is=%d cookie=%d event=%p\n",
		 __func__, group, to_tell, mnt, mask, inode_mark,
		 inode_test_mask, vfsmount_mark, vfsmount_test_mask, data,
		 data_is, cookie, *event);

	if (!inode_test_mask && !vfsmount_test_mask)
		return 0;

	if (group->ops->should_send_event(group, to_tell, inode_mark,
					  vfsmount_mark, mask, data,
					  data_is) == false)
		return 0;

	if (!*event) {
		*event = fsnotify_create_event(to_tell, mask, data,
						data_is, file_name,
						cookie, GFP_KERNEL);
		if (!*event)
			return -ENOMEM;
	}
	return group->ops->handle_event(group, inode_mark, vfsmount_mark, *event);
}

/*
 * This is the main call to fsnotify.  The VFS calls into hook specific functions
 * in linux/fsnotify.h.  Those functions then in turn call here.  Here will call
 * out to all of the registered fsnotify_group.  Those groups can then use the
 * notification event in whatever means they feel necessary.
 */
int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
	     const unsigned char *file_name, u32 cookie)
{
	struct hlist_node *inode_node = NULL, *vfsmount_node = NULL;
	struct fsnotify_mark *inode_mark = NULL, *vfsmount_mark = NULL;
	struct fsnotify_group *inode_group, *vfsmount_group;
	struct fsnotify_event *event = NULL;
	struct vfsmount *mnt;
	int idx, ret = 0;
	/* global tests shouldn't care about events on child only the specific event */
	__u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);

	if (data_is == FSNOTIFY_EVENT_PATH)
		mnt = ((struct path *)data)->mnt;
	else
		mnt = NULL;

	/*
	 * if this is a modify event we may need to clear the ignored masks
	 * otherwise return if neither the inode nor the vfsmount care about
	 * this type of event.
	 */
	if (!(mask & FS_MODIFY) &&
	    !(test_mask & to_tell->i_fsnotify_mask) &&
	    !(mnt && test_mask & mnt->mnt_fsnotify_mask))
		return 0;

	idx = srcu_read_lock(&fsnotify_mark_srcu);

	if ((mask & FS_MODIFY) ||
	    (test_mask & to_tell->i_fsnotify_mask))
		inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first,
					      &fsnotify_mark_srcu);

	if (mnt && ((mask & FS_MODIFY) ||
		    (test_mask & mnt->mnt_fsnotify_mask))) {
		vfsmount_node = srcu_dereference(mnt->mnt_fsnotify_marks.first,
						 &fsnotify_mark_srcu);
		inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first,
					      &fsnotify_mark_srcu);
	}

	while (inode_node || vfsmount_node) {
		inode_group = vfsmount_group = NULL;

		if (inode_node) {
			inode_mark = hlist_entry(srcu_dereference(inode_node, &fsnotify_mark_srcu),
						 struct fsnotify_mark, i.i_list);
			inode_group = inode_mark->group;
		}

		if (vfsmount_node) {
			vfsmount_mark = hlist_entry(srcu_dereference(vfsmount_node, &fsnotify_mark_srcu),
							struct fsnotify_mark, m.m_list);
			vfsmount_group = vfsmount_mark->group;
		}

		if (inode_group > vfsmount_group) {
			/* handle inode */
			ret = send_to_group(to_tell, NULL, inode_mark, NULL, mask, data,
					    data_is, cookie, file_name, &event);
			/* we didn't use the vfsmount_mark */
			vfsmount_group = NULL;
		} else if (vfsmount_group > inode_group) {
			ret = send_to_group(to_tell, mnt, NULL, vfsmount_mark, mask, data,
					    data_is, cookie, file_name, &event);
			inode_group = NULL;
		} else {
			ret = send_to_group(to_tell, mnt, inode_mark, vfsmount_mark,
					    mask, data, data_is, cookie, file_name,
					    &event);
		}

		if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
			goto out;

		if (inode_group)
			inode_node = srcu_dereference(inode_node->next,
						      &fsnotify_mark_srcu);
		if (vfsmount_group)
			vfsmount_node = srcu_dereference(vfsmount_node->next,
							 &fsnotify_mark_srcu);
	}
	ret = 0;
out:
	srcu_read_unlock(&fsnotify_mark_srcu, idx);
	/*
	 * fsnotify_create_event() took a reference so the event can't be cleaned
	 * up while we are still trying to add it to lists, drop that one.
	 */
	if (event)
		fsnotify_put_event(event);

	return ret;
}
EXPORT_SYMBOL_GPL(fsnotify);

static __init int fsnotify_init(void)
{
	int ret;

	BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23);

	ret = init_srcu_struct(&fsnotify_mark_srcu);
	if (ret)
		panic("initializing fsnotify_mark_srcu");

	return 0;
}
core_initcall(fsnotify_init);
Commit	Line	Data
90586523 EP	1	/*
	2	* Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License as published by
	6	* the Free Software Foundation; either version 2, or (at your option)
	7	* any later version.
	8	*
	9	* This program is distributed in the hope that it will be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
	13	*
	14	* You should have received a copy of the GNU General Public License
	15	* along with this program; see the file COPYING. If not, write to
	16	* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
	17	*/
	18
	19	#include <linux/dcache.h>
	20	#include <linux/fs.h>
5a0e3ad6	21	#include <linux/gfp.h>
90586523 EP	22	#include <linux/init.h>
90586523 EP	23	#include <linux/module.h>
7131485a	24	#include <linux/mount.h>
90586523 EP	25	#include <linux/srcu.h>
	26
	27	#include <linux/fsnotify_backend.h>
	28	#include "fsnotify.h"
	29
3be25f49 EP	30	/*
	31	* Clear all of the marks on an inode when it is being evicted from core
	32	*/
	33	void __fsnotify_inode_delete(struct inode *inode)
	34	{
	35	fsnotify_clear_marks_by_inode(inode);
	36	}
	37	EXPORT_SYMBOL_GPL(__fsnotify_inode_delete);
	38
ca9c726e AG	39	void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
	40	{
	41	fsnotify_clear_marks_by_mount(mnt);
	42	}
	43
c28f7e56 EP	44	/*
	45	* Given an inode, first check if we care what happens to our children. Inotify
	46	* and dnotify both tell their parents about events. If we care about any event
	47	* on a child we run all of our children and set a dentry flag saying that the
	48	* parent cares. Thus when an event happens on a child it can quickly tell if
	49	* if there is a need to find a parent and send the event to the parent.
	50	*/
	51	void __fsnotify_update_child_dentry_flags(struct inode *inode)
	52	{
	53	struct dentry *alias;
	54	int watched;
	55
	56	if (!S_ISDIR(inode->i_mode))
	57	return;
	58
	59	/* determine if the children should tell inode about their events */
	60	watched = fsnotify_inode_watches_children(inode);
	61
	62	spin_lock(&dcache_lock);
	63	/* run all of the dentries associated with this inode. Since this is a
	64	* directory, there damn well better only be one item on this list */
	65	list_for_each_entry(alias, &inode->i_dentry, d_alias) {
	66	struct dentry *child;
	67
	68	/* run all of the children of the original inode and fix their
	69	* d_flags to indicate parental interest (their parent is the
	70	* original inode) */
	71	list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
	72	if (!child->d_inode)
	73	continue;
	74
	75	spin_lock(&child->d_lock);
	76	if (watched)
	77	child->d_flags \|= DCACHE_FSNOTIFY_PARENT_WATCHED;
	78	else
	79	child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
	80	spin_unlock(&child->d_lock);
	81	}
	82	}
	83	spin_unlock(&dcache_lock);
	84	}
	85
	86	/* Notify this dentry's parent about a child's events. */
2069601b	87	void __fsnotify_parent(struct path path, struct dentry dentry, __u32 mask)
c28f7e56 EP	88	{
	89	struct dentry *parent;
	90	struct inode *p_inode;
c28f7e56	91
72acc854	92	if (!dentry)
2069601b	93	dentry = path->dentry;
28c60e37	94
c28f7e56 EP	95	if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
	96	return;
	97
4d4eb366	98	parent = dget_parent(dentry);
c28f7e56 EP	99	p_inode = parent->d_inode;
c28f7e56 EP	100
4d4eb366 CH	101	if (unlikely(!fsnotify_inode_watches_children(p_inode)))
	102	__fsnotify_update_child_dentry_flags(p_inode);
	103	else if (p_inode->i_fsnotify_mask & mask) {
c28f7e56 EP	104	/* we are notifying a parent so come up with the new mask which
	105	* specifies these are events which came from a child. */
	106	mask \|= FS_EVENT_ON_CHILD;
	107
2069601b LT	108	if (path)
2069601b LT	109	fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
28c60e37 EP	110	dentry->d_name.name, 0);
	111	else
	112	fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
	113	dentry->d_name.name, 0);
c28f7e56 EP	114	}
c28f7e56 EP	115
4d4eb366	116	dput(parent);
c28f7e56 EP	117	}
	118	EXPORT_SYMBOL_GPL(__fsnotify_parent);
	119
613a807f	120	static int send_to_group(struct inode to_tell, struct vfsmount mnt,
ce8f76fb EP	121	struct fsnotify_mark *inode_mark,
	122	struct fsnotify_mark *vfsmount_mark,
	123	__u32 mask, void *data,
613a807f	124	int data_is, u32 cookie,
3a9b16b4	125	const unsigned char *file_name,
c4ec54b4	126	struct fsnotify_event **event)
7131485a	127	{
faa9560a	128	struct fsnotify_group *group = NULL;
84e1ab4d EP	129	__u32 inode_test_mask = 0;
84e1ab4d EP	130	__u32 vfsmount_test_mask = 0;
613a807f	131
faa9560a EP	132	if (unlikely(!inode_mark && !vfsmount_mark)) {
	133	BUG();
	134	return 0;
	135	}
ce8f76fb EP	136
	137	/* clear ignored on inode modification */
	138	if (mask & FS_MODIFY) {
	139	if (inode_mark &&
	140	!(inode_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
	141	inode_mark->ignored_mask = 0;
	142	if (vfsmount_mark &&
	143	!(vfsmount_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY))
	144	vfsmount_mark->ignored_mask = 0;
	145	}
5ba08e2e	146
ce8f76fb EP	147	/* does the inode mark tell us to do something? */
ce8f76fb EP	148	if (inode_mark) {
faa9560a	149	group = inode_mark->group;
84e1ab4d	150	inode_test_mask = (mask & ~FS_EVENT_ON_CHILD);
ce8f76fb EP	151	inode_test_mask &= inode_mark->mask;
	152	inode_test_mask &= ~inode_mark->ignored_mask;
	153	}
613a807f	154
ce8f76fb EP	155	/* does the vfsmount_mark tell us to do something? */
ce8f76fb EP	156	if (vfsmount_mark) {
84e1ab4d	157	vfsmount_test_mask = (mask & ~FS_EVENT_ON_CHILD);
faa9560a	158	group = vfsmount_mark->group;
ce8f76fb EP	159	vfsmount_test_mask &= vfsmount_mark->mask;
	160	vfsmount_test_mask &= ~vfsmount_mark->ignored_mask;
	161	if (inode_mark)
	162	vfsmount_test_mask &= ~inode_mark->ignored_mask;
	163	}
	164
84e1ab4d EP	165	pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x inode_mark=%p"
	166	" inode_test_mask=%x vfsmount_mark=%p vfsmount_test_mask=%x"
	167	" data=%p data_is=%d cookie=%d event=%p\n",
	168	__func__, group, to_tell, mnt, mask, inode_mark,
	169	inode_test_mask, vfsmount_mark, vfsmount_test_mask, data,
	170	data_is, cookie, *event);
faa9560a	171
ce8f76fb	172	if (!inode_test_mask && !vfsmount_test_mask)
613a807f EP	173	return 0;
613a807f EP	174
1968f5ee	175	if (group->ops->should_send_event(group, to_tell, inode_mark,
ce8f76fb EP	176	vfsmount_mark, mask, data,
ce8f76fb EP	177	data_is) == false)
c4ec54b4	178	return 0;
613a807f	179
7131485a EP	180	if (!*event) {
	181	*event = fsnotify_create_event(to_tell, mask, data,
	182	data_is, file_name,
	183	cookie, GFP_KERNEL);
7131485a	184	if (!*event)
c4ec54b4	185	return -ENOMEM;
7131485a	186	}
ce8f76fb	187	return group->ops->handle_event(group, inode_mark, vfsmount_mark, *event);
7131485a EP	188	}
7131485a EP	189
90586523 EP	190	/*
	191	* This is the main call to fsnotify. The VFS calls into hook specific functions
	192	* in linux/fsnotify.h. Those functions then in turn call here. Here will call
	193	* out to all of the registered fsnotify_group. Those groups can then use the
	194	* notification event in whatever means they feel necessary.
	195	*/
c4ec54b4 EP	196	int fsnotify(struct inode to_tell, __u32 mask, void data, int data_is,
c4ec54b4 EP	197	const unsigned char *file_name, u32 cookie)
90586523	198	{
84e1ab4d	199	struct hlist_node inode_node = NULL, vfsmount_node = NULL;
613a807f EP	200	struct fsnotify_mark inode_mark = NULL, vfsmount_mark = NULL;
613a807f EP	201	struct fsnotify_group inode_group, vfsmount_group;
90586523	202	struct fsnotify_event *event = NULL;
613a807f	203	struct vfsmount *mnt;
c4ec54b4	204	int idx, ret = 0;
e42e2773 EP	205	/* global tests shouldn't care about events on child only the specific event */
e42e2773 EP	206	__u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
90586523	207
2069601b LT	208	if (data_is == FSNOTIFY_EVENT_PATH)
2069601b LT	209	mnt = ((struct path *)data)->mnt;
613a807f EP	210	else
	211	mnt = NULL;
	212
	213	/*
	214	* if this is a modify event we may need to clear the ignored masks
	215	* otherwise return if neither the inode nor the vfsmount care about
	216	* this type of event.
	217	*/
	218	if (!(mask & FS_MODIFY) &&
	219	!(test_mask & to_tell->i_fsnotify_mask) &&
	220	!(mnt && test_mask & mnt->mnt_fsnotify_mask))
	221	return 0;
3a9fb89f	222
75c1be48	223	idx = srcu_read_lock(&fsnotify_mark_srcu);
7131485a	224
613a807f EP	225	if ((mask & FS_MODIFY) \|\|
613a807f EP	226	(test_mask & to_tell->i_fsnotify_mask))
ce8f76fb EP	227	inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first,
ce8f76fb EP	228	&fsnotify_mark_srcu);
613a807f	229
84e1ab4d EP	230	if (mnt && ((mask & FS_MODIFY) \|\|
	231	(test_mask & mnt->mnt_fsnotify_mask))) {
	232	vfsmount_node = srcu_dereference(mnt->mnt_fsnotify_marks.first,
	233	&fsnotify_mark_srcu);
	234	inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first,
	235	&fsnotify_mark_srcu);
90586523	236	}
75c1be48	237
613a807f	238	while (inode_node \|\| vfsmount_node) {
f72adfd5	239	inode_group = vfsmount_group = NULL;
5f3f259f	240
613a807f EP	241	if (inode_node) {
	242	inode_mark = hlist_entry(srcu_dereference(inode_node, &fsnotify_mark_srcu),
	243	struct fsnotify_mark, i.i_list);
	244	inode_group = inode_mark->group;
f72adfd5	245	}
613a807f EP	246
	247	if (vfsmount_node) {
	248	vfsmount_mark = hlist_entry(srcu_dereference(vfsmount_node, &fsnotify_mark_srcu),
	249	struct fsnotify_mark, m.m_list);
	250	vfsmount_group = vfsmount_mark->group;
f72adfd5	251	}
613a807f	252
f72adfd5	253	if (inode_group > vfsmount_group) {
613a807f	254	/* handle inode */
ff8bcbd0 EP	255	ret = send_to_group(to_tell, NULL, inode_mark, NULL, mask, data,
ff8bcbd0 EP	256	data_is, cookie, file_name, &event);
92b4678e EP	257	/* we didn't use the vfsmount_mark */
92b4678e EP	258	vfsmount_group = NULL;
f72adfd5	259	} else if (vfsmount_group > inode_group) {
ff8bcbd0 EP	260	ret = send_to_group(to_tell, mnt, NULL, vfsmount_mark, mask, data,
ff8bcbd0 EP	261	data_is, cookie, file_name, &event);
92b4678e	262	inode_group = NULL;
613a807f	263	} else {
ff8bcbd0 EP	264	ret = send_to_group(to_tell, mnt, inode_mark, vfsmount_mark,
	265	mask, data, data_is, cookie, file_name,
	266	&event);
7131485a	267	}
613a807f	268
ff8bcbd0 EP	269	if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
	270	goto out;
	271
92b4678e	272	if (inode_group)
ce8f76fb EP	273	inode_node = srcu_dereference(inode_node->next,
ce8f76fb EP	274	&fsnotify_mark_srcu);
92b4678e	275	if (vfsmount_group)
ce8f76fb EP	276	vfsmount_node = srcu_dereference(vfsmount_node->next,
ce8f76fb EP	277	&fsnotify_mark_srcu);
7131485a	278	}
ff8bcbd0 EP	279	ret = 0;
ff8bcbd0 EP	280	out:
75c1be48	281	srcu_read_unlock(&fsnotify_mark_srcu, idx);
90586523 EP	282	/*
	283	* fsnotify_create_event() took a reference so the event can't be cleaned
	284	* up while we are still trying to add it to lists, drop that one.
	285	*/
	286	if (event)
	287	fsnotify_put_event(event);
c4ec54b4	288
98b5c10d	289	return ret;
90586523 EP	290	}
	291	EXPORT_SYMBOL_GPL(fsnotify);
	292
	293	static __init int fsnotify_init(void)
	294	{
75c1be48 EP	295	int ret;
75c1be48 EP	296
20dee624 EP	297	BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23);
20dee624 EP	298
75c1be48 EP	299	ret = init_srcu_struct(&fsnotify_mark_srcu);
	300	if (ret)
	301	panic("initializing fsnotify_mark_srcu");
	302
	303	return 0;
90586523	304	}
75c1be48	305	core_initcall(fsnotify_init);