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* Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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#include <linux/dcache.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/srcu.h>
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#include <linux/fsnotify_backend.h>
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* Clear all of the marks on an inode when it is being evicted from core
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void __fsnotify_inode_delete(struct inode *inode)
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fsnotify_clear_marks_by_inode(inode);
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EXPORT_SYMBOL_GPL(__fsnotify_inode_delete);
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* Given an inode, first check if we care what happens to our children. Inotify
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* and dnotify both tell their parents about events. If we care about any event
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* on a child we run all of our children and set a dentry flag saying that the
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* parent cares. Thus when an event happens on a child it can quickly tell if
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* if there is a need to find a parent and send the event to the parent.
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void __fsnotify_update_child_dentry_flags(struct inode *inode)
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if (!S_ISDIR(inode->i_mode))
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/* determine if the children should tell inode about their events */
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watched = fsnotify_inode_watches_children(inode);
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spin_lock(&dcache_lock);
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/* run all of the dentries associated with this inode. Since this is a
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* directory, there damn well better only be one item on this list */
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list_for_each_entry(alias, &inode->i_dentry, d_alias) {
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/* run all of the children of the original inode and fix their
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* d_flags to indicate parental interest (their parent is the
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list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) {
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spin_lock(&child->d_lock);
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child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
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child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
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spin_unlock(&child->d_lock);
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spin_unlock(&dcache_lock);
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/* Notify this dentry's parent about a child's events. */
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void __fsnotify_parent(struct dentry *dentry, __u32 mask)
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struct dentry *parent;
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struct inode *p_inode;
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bool should_update_children = false;
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if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED))
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spin_lock(&dentry->d_lock);
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parent = dentry->d_parent;
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p_inode = parent->d_inode;
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if (fsnotify_inode_watches_children(p_inode)) {
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if (p_inode->i_fsnotify_mask & mask) {
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* The parent doesn't care about events on it's children but
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* at least one child thought it did. We need to run all the
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* children and update their d_flags to let them know p_inode
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* doesn't care about them any more.
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should_update_children = true;
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spin_unlock(&dentry->d_lock);
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/* we are notifying a parent so come up with the new mask which
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* specifies these are events which came from a child. */
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mask |= FS_EVENT_ON_CHILD;
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fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
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dentry->d_name.name, 0);
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if (unlikely(should_update_children)) {
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__fsnotify_update_child_dentry_flags(p_inode);
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EXPORT_SYMBOL_GPL(__fsnotify_parent);
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* This is the main call to fsnotify. The VFS calls into hook specific functions
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* in linux/fsnotify.h. Those functions then in turn call here. Here will call
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* out to all of the registered fsnotify_group. Those groups can then use the
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* notification event in whatever means they feel necessary.
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void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, const char *file_name, u32 cookie)
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struct fsnotify_group *group;
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struct fsnotify_event *event = NULL;
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/* global tests shouldn't care about events on child only the specific event */
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__u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
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if (list_empty(&fsnotify_groups))
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if (!(test_mask & fsnotify_mask))
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if (!(test_mask & to_tell->i_fsnotify_mask))
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* SRCU!! the groups list is very very much read only and the path is
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* very hot. The VAST majority of events are not going to need to do
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* anything other than walk the list so it's crazy to pre-allocate.
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idx = srcu_read_lock(&fsnotify_grp_srcu);
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list_for_each_entry_rcu(group, &fsnotify_groups, group_list) {
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if (test_mask & group->mask) {
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if (!group->ops->should_send_event(group, to_tell, mask))
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event = fsnotify_create_event(to_tell, mask, data,
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data_is, file_name, cookie,
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/* shit, we OOM'd and now we can't tell, maybe
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* someday someone else will want to do something
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group->ops->handle_event(group, event);
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srcu_read_unlock(&fsnotify_grp_srcu, idx);
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* fsnotify_create_event() took a reference so the event can't be cleaned
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* up while we are still trying to add it to lists, drop that one.
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fsnotify_put_event(event);
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EXPORT_SYMBOL_GPL(fsnotify);
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static __init int fsnotify_init(void)
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return init_srcu_struct(&fsnotify_grp_srcu);
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subsys_initcall(fsnotify_init);