246 строки
7.3 KiB
C
246 строки
7.3 KiB
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;
|
|
bool send = false;
|
|
bool should_update_children = false;
|
|
|
|
if (!dentry)
|
|
dentry = path->dentry;
|
|
|
|
if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
|
|
return;
|
|
|
|
spin_lock(&dentry->d_lock);
|
|
parent = dentry->d_parent;
|
|
p_inode = parent->d_inode;
|
|
|
|
if (fsnotify_inode_watches_children(p_inode)) {
|
|
if (p_inode->i_fsnotify_mask & mask) {
|
|
dget(parent);
|
|
send = true;
|
|
}
|
|
} else {
|
|
/*
|
|
* The parent doesn't care about events on it's children but
|
|
* at least one child thought it did. We need to run all the
|
|
* children and update their d_flags to let them know p_inode
|
|
* doesn't care about them any more.
|
|
*/
|
|
dget(parent);
|
|
should_update_children = true;
|
|
}
|
|
|
|
spin_unlock(&dentry->d_lock);
|
|
|
|
if (send) {
|
|
/* 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);
|
|
}
|
|
|
|
if (unlikely(should_update_children)) {
|
|
__fsnotify_update_child_dentry_flags(p_inode);
|
|
dput(parent);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(__fsnotify_parent);
|
|
|
|
static void send_to_group(struct fsnotify_group *group, struct inode *to_tell,
|
|
struct vfsmount *mnt, __u32 mask, void *data,
|
|
int data_is, u32 cookie, const char *file_name,
|
|
struct fsnotify_event **event)
|
|
{
|
|
if (!group->ops->should_send_event(group, to_tell, mnt, mask,
|
|
data, data_is))
|
|
return;
|
|
if (!*event) {
|
|
*event = fsnotify_create_event(to_tell, mask, data,
|
|
data_is, file_name,
|
|
cookie, GFP_KERNEL);
|
|
/*
|
|
* shit, we OOM'd and now we can't tell, maybe
|
|
* someday someone else will want to do something
|
|
* here
|
|
*/
|
|
if (!*event)
|
|
return;
|
|
}
|
|
group->ops->handle_event(group, *event);
|
|
}
|
|
|
|
static bool needed_by_vfsmount(__u32 test_mask, struct vfsmount *mnt)
|
|
{
|
|
if (!mnt)
|
|
return false;
|
|
|
|
return (test_mask & mnt->mnt_fsnotify_mask);
|
|
}
|
|
/*
|
|
* 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.
|
|
*/
|
|
void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, const char *file_name, u32 cookie)
|
|
{
|
|
struct fsnotify_group *group;
|
|
struct fsnotify_event *event = NULL;
|
|
struct vfsmount *mnt = NULL;
|
|
int idx;
|
|
/* global tests shouldn't care about events on child only the specific event */
|
|
__u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
|
|
|
|
/* if no fsnotify listeners, nothing to do */
|
|
if (list_empty(&fsnotify_inode_groups) &&
|
|
list_empty(&fsnotify_vfsmount_groups))
|
|
return;
|
|
|
|
/* if none of the directed listeners or vfsmount listeners care */
|
|
if (!(test_mask & fsnotify_inode_mask) &&
|
|
!(test_mask & fsnotify_vfsmount_mask))
|
|
return;
|
|
|
|
if (data_is == FSNOTIFY_EVENT_PATH)
|
|
mnt = ((struct path *)data)->mnt;
|
|
|
|
/* if this inode's directed listeners don't care and nothing on the vfsmount
|
|
* listeners list cares, nothing to do */
|
|
if (!(test_mask & to_tell->i_fsnotify_mask) &&
|
|
!needed_by_vfsmount(test_mask, mnt))
|
|
return;
|
|
|
|
/*
|
|
* SRCU!! the groups list is very very much read only and the path is
|
|
* very hot. The VAST majority of events are not going to need to do
|
|
* anything other than walk the list so it's crazy to pre-allocate.
|
|
*/
|
|
idx = srcu_read_lock(&fsnotify_grp_srcu);
|
|
|
|
if (test_mask & to_tell->i_fsnotify_mask) {
|
|
list_for_each_entry_rcu(group, &fsnotify_inode_groups, inode_group_list) {
|
|
if (test_mask & group->mask) {
|
|
send_to_group(group, to_tell, NULL, mask, data, data_is,
|
|
cookie, file_name, &event);
|
|
}
|
|
}
|
|
}
|
|
if (needed_by_vfsmount(test_mask, mnt)) {
|
|
list_for_each_entry_rcu(group, &fsnotify_vfsmount_groups, vfsmount_group_list) {
|
|
if (test_mask & group->mask) {
|
|
send_to_group(group, to_tell, mnt, mask, data, data_is,
|
|
cookie, file_name, &event);
|
|
}
|
|
}
|
|
}
|
|
|
|
srcu_read_unlock(&fsnotify_grp_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);
|
|
}
|
|
EXPORT_SYMBOL_GPL(fsnotify);
|
|
|
|
static __init int fsnotify_init(void)
|
|
{
|
|
return init_srcu_struct(&fsnotify_grp_srcu);
|
|
}
|
|
subsys_initcall(fsnotify_init);
|