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> |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 24 | #include <linux/mount.h> |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 25 | #include <linux/srcu.h> |
| 26 | |
| 27 | #include <linux/fsnotify_backend.h> |
| 28 | #include "fsnotify.h" |
| 29 | |
| 30 | /* |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 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 | |
| 39 | /* |
Eric Paris | c28f7e5 | 2009-05-21 17:01:29 -0400 | [diff] [blame] | 40 | * Given an inode, first check if we care what happens to our children. Inotify |
| 41 | * and dnotify both tell their parents about events. If we care about any event |
| 42 | * on a child we run all of our children and set a dentry flag saying that the |
| 43 | * parent cares. Thus when an event happens on a child it can quickly tell if |
| 44 | * if there is a need to find a parent and send the event to the parent. |
| 45 | */ |
| 46 | void __fsnotify_update_child_dentry_flags(struct inode *inode) |
| 47 | { |
| 48 | struct dentry *alias; |
| 49 | int watched; |
| 50 | |
| 51 | if (!S_ISDIR(inode->i_mode)) |
| 52 | return; |
| 53 | |
| 54 | /* determine if the children should tell inode about their events */ |
| 55 | watched = fsnotify_inode_watches_children(inode); |
| 56 | |
| 57 | spin_lock(&dcache_lock); |
| 58 | /* run all of the dentries associated with this inode. Since this is a |
| 59 | * directory, there damn well better only be one item on this list */ |
| 60 | list_for_each_entry(alias, &inode->i_dentry, d_alias) { |
| 61 | struct dentry *child; |
| 62 | |
| 63 | /* run all of the children of the original inode and fix their |
| 64 | * d_flags to indicate parental interest (their parent is the |
| 65 | * original inode) */ |
| 66 | list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) { |
| 67 | if (!child->d_inode) |
| 68 | continue; |
| 69 | |
| 70 | spin_lock(&child->d_lock); |
| 71 | if (watched) |
| 72 | child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; |
| 73 | else |
| 74 | child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; |
| 75 | spin_unlock(&child->d_lock); |
| 76 | } |
| 77 | } |
| 78 | spin_unlock(&dcache_lock); |
| 79 | } |
| 80 | |
| 81 | /* Notify this dentry's parent about a child's events. */ |
Eric Paris | 28c60e3 | 2009-12-17 21:24:21 -0500 | [diff] [blame] | 82 | void __fsnotify_parent(struct file *file, struct dentry *dentry, __u32 mask) |
Eric Paris | c28f7e5 | 2009-05-21 17:01:29 -0400 | [diff] [blame] | 83 | { |
| 84 | struct dentry *parent; |
| 85 | struct inode *p_inode; |
| 86 | bool send = false; |
| 87 | bool should_update_children = false; |
| 88 | |
Eric Paris | 28c60e3 | 2009-12-17 21:24:21 -0500 | [diff] [blame] | 89 | if (file) |
| 90 | dentry = file->f_path.dentry; |
| 91 | |
Eric Paris | c28f7e5 | 2009-05-21 17:01:29 -0400 | [diff] [blame] | 92 | if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED)) |
| 93 | return; |
| 94 | |
| 95 | spin_lock(&dentry->d_lock); |
| 96 | parent = dentry->d_parent; |
| 97 | p_inode = parent->d_inode; |
| 98 | |
| 99 | if (fsnotify_inode_watches_children(p_inode)) { |
| 100 | if (p_inode->i_fsnotify_mask & mask) { |
| 101 | dget(parent); |
| 102 | send = true; |
| 103 | } |
| 104 | } else { |
| 105 | /* |
| 106 | * The parent doesn't care about events on it's children but |
| 107 | * at least one child thought it did. We need to run all the |
| 108 | * children and update their d_flags to let them know p_inode |
| 109 | * doesn't care about them any more. |
| 110 | */ |
| 111 | dget(parent); |
| 112 | should_update_children = true; |
| 113 | } |
| 114 | |
| 115 | spin_unlock(&dentry->d_lock); |
| 116 | |
| 117 | if (send) { |
| 118 | /* we are notifying a parent so come up with the new mask which |
| 119 | * specifies these are events which came from a child. */ |
| 120 | mask |= FS_EVENT_ON_CHILD; |
| 121 | |
Eric Paris | 28c60e3 | 2009-12-17 21:24:21 -0500 | [diff] [blame] | 122 | if (file) |
| 123 | fsnotify(p_inode, mask, file, FSNOTIFY_EVENT_FILE, |
| 124 | dentry->d_name.name, 0); |
| 125 | else |
| 126 | fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE, |
| 127 | dentry->d_name.name, 0); |
Eric Paris | c28f7e5 | 2009-05-21 17:01:29 -0400 | [diff] [blame] | 128 | dput(parent); |
| 129 | } |
| 130 | |
| 131 | if (unlikely(should_update_children)) { |
| 132 | __fsnotify_update_child_dentry_flags(p_inode); |
| 133 | dput(parent); |
| 134 | } |
| 135 | } |
| 136 | EXPORT_SYMBOL_GPL(__fsnotify_parent); |
| 137 | |
Eric Paris | 3a9fb89 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 138 | static void send_to_group(struct fsnotify_group *group, struct inode *to_tell, |
| 139 | struct vfsmount *mnt, __u32 mask, void *data, |
| 140 | int data_is, u32 cookie, const char *file_name, |
| 141 | struct fsnotify_event **event) |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 142 | { |
Eric Paris | 3a9fb89 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 143 | if (!group->ops->should_send_event(group, to_tell, mnt, mask, |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 144 | data, data_is)) |
| 145 | return; |
| 146 | if (!*event) { |
| 147 | *event = fsnotify_create_event(to_tell, mask, data, |
| 148 | data_is, file_name, |
| 149 | cookie, GFP_KERNEL); |
| 150 | /* |
| 151 | * shit, we OOM'd and now we can't tell, maybe |
| 152 | * someday someone else will want to do something |
| 153 | * here |
| 154 | */ |
| 155 | if (!*event) |
| 156 | return; |
| 157 | } |
| 158 | group->ops->handle_event(group, *event); |
| 159 | } |
| 160 | |
Eric Paris | 3a9fb89 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 161 | static bool needed_by_vfsmount(__u32 test_mask, struct vfsmount *mnt) |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 162 | { |
Eric Paris | 3a9fb89 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 163 | if (!mnt) |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 164 | return false; |
| 165 | |
| 166 | /* hook in this when mnt->mnt_fsnotify_mask is defined */ |
| 167 | /* return (test_mask & path->mnt->mnt_fsnotify_mask); */ |
| 168 | return false; |
| 169 | } |
Eric Paris | c28f7e5 | 2009-05-21 17:01:29 -0400 | [diff] [blame] | 170 | /* |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 171 | * This is the main call to fsnotify. The VFS calls into hook specific functions |
| 172 | * in linux/fsnotify.h. Those functions then in turn call here. Here will call |
| 173 | * out to all of the registered fsnotify_group. Those groups can then use the |
| 174 | * notification event in whatever means they feel necessary. |
| 175 | */ |
Eric Paris | 47882c6 | 2009-05-21 17:01:47 -0400 | [diff] [blame] | 176 | 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] | 177 | { |
| 178 | struct fsnotify_group *group; |
| 179 | struct fsnotify_event *event = NULL; |
Eric Paris | 3a9fb89 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 180 | struct vfsmount *mnt = NULL; |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 181 | int idx; |
Eric Paris | e42e277 | 2009-06-11 11:09:47 -0400 | [diff] [blame] | 182 | /* global tests shouldn't care about events on child only the specific event */ |
| 183 | __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD); |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 184 | |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 185 | /* if no fsnotify listeners, nothing to do */ |
| 186 | if (list_empty(&fsnotify_inode_groups) && |
| 187 | list_empty(&fsnotify_vfsmount_groups)) |
| 188 | return; |
| 189 | |
| 190 | /* if none of the directed listeners or vfsmount listeners care */ |
| 191 | if (!(test_mask & fsnotify_inode_mask) && |
| 192 | !(test_mask & fsnotify_vfsmount_mask)) |
| 193 | return; |
| 194 | |
Eric Paris | 3a9fb89 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 195 | if (data_is == FSNOTIFY_EVENT_PATH) |
| 196 | mnt = ((struct path *)data)->mnt; |
| 197 | else if (data_is == FSNOTIFY_EVENT_FILE) |
| 198 | mnt = ((struct file *)data)->f_path.mnt; |
| 199 | |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 200 | /* if this inode's directed listeners don't care and nothing on the vfsmount |
| 201 | * listeners list cares, nothing to do */ |
| 202 | if (!(test_mask & to_tell->i_fsnotify_mask) && |
Eric Paris | 3a9fb89 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 203 | !needed_by_vfsmount(test_mask, mnt)) |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 204 | return; |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 205 | |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 206 | /* |
| 207 | * SRCU!! the groups list is very very much read only and the path is |
| 208 | * very hot. The VAST majority of events are not going to need to do |
| 209 | * anything other than walk the list so it's crazy to pre-allocate. |
| 210 | */ |
| 211 | idx = srcu_read_lock(&fsnotify_grp_srcu); |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 212 | |
| 213 | if (test_mask & to_tell->i_fsnotify_mask) { |
| 214 | list_for_each_entry_rcu(group, &fsnotify_inode_groups, inode_group_list) { |
| 215 | if (test_mask & group->mask) { |
Eric Paris | 3a9fb89 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 216 | send_to_group(group, to_tell, NULL, mask, data, data_is, |
| 217 | cookie, file_name, &event); |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 218 | } |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 219 | } |
| 220 | } |
Eric Paris | 3a9fb89 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 221 | if (needed_by_vfsmount(test_mask, mnt)) { |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 222 | list_for_each_entry_rcu(group, &fsnotify_vfsmount_groups, vfsmount_group_list) { |
| 223 | if (test_mask & group->mask) { |
Eric Paris | 3a9fb89 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 224 | send_to_group(group, to_tell, mnt, mask, data, data_is, |
| 225 | cookie, file_name, &event); |
Eric Paris | 7131485 | 2009-12-17 21:24:23 -0500 | [diff] [blame] | 226 | } |
| 227 | } |
| 228 | } |
| 229 | |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 230 | srcu_read_unlock(&fsnotify_grp_srcu, idx); |
| 231 | /* |
| 232 | * fsnotify_create_event() took a reference so the event can't be cleaned |
| 233 | * up while we are still trying to add it to lists, drop that one. |
| 234 | */ |
| 235 | if (event) |
| 236 | fsnotify_put_event(event); |
| 237 | } |
| 238 | EXPORT_SYMBOL_GPL(fsnotify); |
| 239 | |
| 240 | static __init int fsnotify_init(void) |
| 241 | { |
| 242 | return init_srcu_struct(&fsnotify_grp_srcu); |
| 243 | } |
| 244 | subsys_initcall(fsnotify_init); |