fs/notify/fsnotify.c - maze/linux - Git at Google

 /*
  *  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"
 #include "../mount.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(&inode->i_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) */
 		spin_lock(&alias->d_lock);
 		list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
 			if (!child->d_inode)
 				continue;

 			spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
 			if (watched)
 				child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
 			else
 				child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
 			spin_unlock(&child->d_lock);
 		}
 		spin_unlock(&alias->d_lock);
 	}
 	spin_unlock(&inode->i_lock);
 }

 /* Notify this dentry's parent about a child's events. */
 int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
 {
 	struct dentry *parent;
 	struct inode *p_inode;
 	int ret = 0;

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

 	if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
 		return 0;

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

 	dput(parent);

 	return ret;
 }
 EXPORT_SYMBOL_GPL(__fsnotify_parent);

 static int send_to_group(struct inode *to_tell,
 			 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 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, 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 mount *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 = real_mount(((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, 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, NULL, vfsmount_mark, mask, data,
 					    data_is, cookie, file_name, &event);
 			inode_group = NULL;
 		} else {
 			ret = send_to_group(to_tell, 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);
	/*
	* 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"
	#include "../mount.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(&inode->i_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) */
	spin_lock(&alias->d_lock);
	list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
	if (!child->d_inode)
	continue;

	spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED);
	if (watched)
	child->d_flags \|= DCACHE_FSNOTIFY_PARENT_WATCHED;
	else
	child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
	spin_unlock(&child->d_lock);
	}
	spin_unlock(&alias->d_lock);
	}
	spin_unlock(&inode->i_lock);
	}

	/* Notify this dentry's parent about a child's events. */
	int __fsnotify_parent(struct path path, struct dentry dentry, __u32 mask)
	{
	struct dentry *parent;
	struct inode *p_inode;
	int ret = 0;

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

	if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
	return 0;

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

	dput(parent);

	return ret;
	}
	EXPORT_SYMBOL_GPL(__fsnotify_parent);

	static int send_to_group(struct inode *to_tell,
	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 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, 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 mount *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 = real_mount(((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, 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, NULL, vfsmount_mark, mask, data,
	data_is, cookie, file_name, &event);
	inode_group = NULL;
	} else {
	ret = send_to_group(to_tell, 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);