Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 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> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 21 | #include <linux/gfp.h> |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 22 | #include <linux/init.h> |
| 23 | #include <linux/module.h> |
| 24 | #include <linux/srcu.h> |
| 25 | |
| 26 | #include <linux/fsnotify_backend.h> |
| 27 | #include "fsnotify.h" |
| 28 | |
| 29 | /* |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 30 | * Clear all of the marks on an inode when it is being evicted from core |
| 31 | */ |
| 32 | void __fsnotify_inode_delete(struct inode *inode) |
| 33 | { |
| 34 | fsnotify_clear_marks_by_inode(inode); |
| 35 | } |
| 36 | EXPORT_SYMBOL_GPL(__fsnotify_inode_delete); |
| 37 | |
| 38 | /* |
Eric Paris | c28f7e5 | 2009-05-21 17:01:29 -0400 | [diff] [blame] | 39 | * Given an inode, first check if we care what happens to our children. Inotify |
| 40 | * and dnotify both tell their parents about events. If we care about any event |
| 41 | * on a child we run all of our children and set a dentry flag saying that the |
| 42 | * parent cares. Thus when an event happens on a child it can quickly tell if |
| 43 | * if there is a need to find a parent and send the event to the parent. |
| 44 | */ |
| 45 | void __fsnotify_update_child_dentry_flags(struct inode *inode) |
| 46 | { |
| 47 | struct dentry *alias; |
| 48 | int watched; |
| 49 | |
| 50 | if (!S_ISDIR(inode->i_mode)) |
| 51 | return; |
| 52 | |
| 53 | /* determine if the children should tell inode about their events */ |
| 54 | watched = fsnotify_inode_watches_children(inode); |
| 55 | |
| 56 | spin_lock(&dcache_lock); |
| 57 | /* run all of the dentries associated with this inode. Since this is a |
| 58 | * directory, there damn well better only be one item on this list */ |
| 59 | list_for_each_entry(alias, &inode->i_dentry, d_alias) { |
| 60 | struct dentry *child; |
| 61 | |
| 62 | /* run all of the children of the original inode and fix their |
| 63 | * d_flags to indicate parental interest (their parent is the |
| 64 | * original inode) */ |
| 65 | list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) { |
| 66 | if (!child->d_inode) |
| 67 | continue; |
| 68 | |
| 69 | spin_lock(&child->d_lock); |
| 70 | if (watched) |
| 71 | child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; |
| 72 | else |
| 73 | child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; |
| 74 | spin_unlock(&child->d_lock); |
| 75 | } |
| 76 | } |
| 77 | spin_unlock(&dcache_lock); |
| 78 | } |
| 79 | |
| 80 | /* Notify this dentry's parent about a child's events. */ |
| 81 | void __fsnotify_parent(struct dentry *dentry, __u32 mask) |
| 82 | { |
| 83 | struct dentry *parent; |
| 84 | struct inode *p_inode; |
| 85 | bool send = false; |
| 86 | bool should_update_children = false; |
| 87 | |
| 88 | if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED)) |
| 89 | return; |
| 90 | |
| 91 | spin_lock(&dentry->d_lock); |
| 92 | parent = dentry->d_parent; |
| 93 | p_inode = parent->d_inode; |
| 94 | |
| 95 | if (fsnotify_inode_watches_children(p_inode)) { |
| 96 | if (p_inode->i_fsnotify_mask & mask) { |
| 97 | dget(parent); |
| 98 | send = true; |
| 99 | } |
| 100 | } else { |
| 101 | /* |
| 102 | * The parent doesn't care about events on it's children but |
| 103 | * at least one child thought it did. We need to run all the |
| 104 | * children and update their d_flags to let them know p_inode |
| 105 | * doesn't care about them any more. |
| 106 | */ |
| 107 | dget(parent); |
| 108 | should_update_children = true; |
| 109 | } |
| 110 | |
| 111 | spin_unlock(&dentry->d_lock); |
| 112 | |
| 113 | if (send) { |
| 114 | /* we are notifying a parent so come up with the new mask which |
| 115 | * specifies these are events which came from a child. */ |
| 116 | mask |= FS_EVENT_ON_CHILD; |
| 117 | |
Eric Paris | 62ffe5d | 2009-05-21 17:01:43 -0400 | [diff] [blame] | 118 | fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE, |
Eric Paris | 47882c6 | 2009-05-21 17:01:47 -0400 | [diff] [blame] | 119 | dentry->d_name.name, 0); |
Eric Paris | c28f7e5 | 2009-05-21 17:01:29 -0400 | [diff] [blame] | 120 | dput(parent); |
| 121 | } |
| 122 | |
| 123 | if (unlikely(should_update_children)) { |
| 124 | __fsnotify_update_child_dentry_flags(p_inode); |
| 125 | dput(parent); |
| 126 | } |
| 127 | } |
| 128 | EXPORT_SYMBOL_GPL(__fsnotify_parent); |
| 129 | |
| 130 | /* |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 131 | * This is the main call to fsnotify. The VFS calls into hook specific functions |
| 132 | * in linux/fsnotify.h. Those functions then in turn call here. Here will call |
| 133 | * out to all of the registered fsnotify_group. Those groups can then use the |
| 134 | * notification event in whatever means they feel necessary. |
| 135 | */ |
Eric Paris | 47882c6 | 2009-05-21 17:01:47 -0400 | [diff] [blame] | 136 | void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, const char *file_name, u32 cookie) |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 137 | { |
| 138 | struct fsnotify_group *group; |
| 139 | struct fsnotify_event *event = NULL; |
| 140 | int idx; |
Eric Paris | e42e277 | 2009-06-11 11:09:47 -0400 | [diff] [blame] | 141 | /* global tests shouldn't care about events on child only the specific event */ |
| 142 | __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD); |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 143 | |
| 144 | if (list_empty(&fsnotify_groups)) |
| 145 | return; |
| 146 | |
Eric Paris | e42e277 | 2009-06-11 11:09:47 -0400 | [diff] [blame] | 147 | if (!(test_mask & fsnotify_mask)) |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 148 | return; |
| 149 | |
Eric Paris | e42e277 | 2009-06-11 11:09:47 -0400 | [diff] [blame] | 150 | if (!(test_mask & to_tell->i_fsnotify_mask)) |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 151 | return; |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 152 | /* |
| 153 | * SRCU!! the groups list is very very much read only and the path is |
| 154 | * very hot. The VAST majority of events are not going to need to do |
| 155 | * anything other than walk the list so it's crazy to pre-allocate. |
| 156 | */ |
| 157 | idx = srcu_read_lock(&fsnotify_grp_srcu); |
| 158 | list_for_each_entry_rcu(group, &fsnotify_groups, group_list) { |
Eric Paris | e42e277 | 2009-06-11 11:09:47 -0400 | [diff] [blame] | 159 | if (test_mask & group->mask) { |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 160 | if (!group->ops->should_send_event(group, to_tell, mask)) |
| 161 | continue; |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 162 | if (!event) { |
Eric Paris | f44aebc | 2009-07-15 15:49:52 -0400 | [diff] [blame] | 163 | event = fsnotify_create_event(to_tell, mask, data, |
| 164 | data_is, file_name, cookie, |
| 165 | GFP_KERNEL); |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 166 | /* shit, we OOM'd and now we can't tell, maybe |
| 167 | * someday someone else will want to do something |
| 168 | * here */ |
| 169 | if (!event) |
| 170 | break; |
| 171 | } |
| 172 | group->ops->handle_event(group, event); |
| 173 | } |
| 174 | } |
| 175 | srcu_read_unlock(&fsnotify_grp_srcu, idx); |
| 176 | /* |
| 177 | * fsnotify_create_event() took a reference so the event can't be cleaned |
| 178 | * up while we are still trying to add it to lists, drop that one. |
| 179 | */ |
| 180 | if (event) |
| 181 | fsnotify_put_event(event); |
| 182 | } |
| 183 | EXPORT_SYMBOL_GPL(fsnotify); |
| 184 | |
| 185 | static __init int fsnotify_init(void) |
| 186 | { |
| 187 | return init_srcu_struct(&fsnotify_grp_srcu); |
| 188 | } |
| 189 | subsys_initcall(fsnotify_init); |