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> 21 #include <linux/gfp.h> 22 #include <linux/init.h> 23 #include <linux/module.h> 24 #include <linux/mount.h> 25 #include <linux/srcu.h> 26 27 #include <linux/fsnotify_backend.h> 28 #include "fsnotify.h" 29 30 /* 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 void __fsnotify_vfsmount_delete(struct vfsmount *mnt) 40 { 41 fsnotify_clear_marks_by_mount(mnt); 42 } 43 44 /* 45 * Given an inode, first check if we care what happens to our children. Inotify 46 * and dnotify both tell their parents about events. If we care about any event 47 * on a child we run all of our children and set a dentry flag saying that the 48 * parent cares. Thus when an event happens on a child it can quickly tell if 49 * if there is a need to find a parent and send the event to the parent. 50 */ 51 void __fsnotify_update_child_dentry_flags(struct inode *inode) 52 { 53 struct dentry *alias; 54 int watched; 55 56 if (!S_ISDIR(inode->i_mode)) 57 return; 58 59 /* determine if the children should tell inode about their events */ 60 watched = fsnotify_inode_watches_children(inode); 61 62 spin_lock(&dcache_lock); 63 /* run all of the dentries associated with this inode. Since this is a 64 * directory, there damn well better only be one item on this list */ 65 list_for_each_entry(alias, &inode->i_dentry, d_alias) { 66 struct dentry *child; 67 68 /* run all of the children of the original inode and fix their 69 * d_flags to indicate parental interest (their parent is the 70 * original inode) */ 71 list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) { 72 if (!child->d_inode) 73 continue; 74 75 spin_lock(&child->d_lock); 76 if (watched) 77 child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; 78 else 79 child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; 80 spin_unlock(&child->d_lock); 81 } 82 } 83 spin_unlock(&dcache_lock); 84 } 85 86 /* Notify this dentry's parent about a child's events. */ 87 void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) 88 { 89 struct dentry *parent; 90 struct inode *p_inode; 91 bool send = false; 92 bool should_update_children = false; 93 94 if (!dentry) 95 dentry = path->dentry; 96 97 if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED)) 98 return; 99 100 spin_lock(&dentry->d_lock); 101 parent = dentry->d_parent; 102 p_inode = parent->d_inode; 103 104 if (fsnotify_inode_watches_children(p_inode)) { 105 if (p_inode->i_fsnotify_mask & mask) { 106 dget(parent); 107 send = true; 108 } 109 } else { 110 /* 111 * The parent doesn't care about events on it's children but 112 * at least one child thought it did. We need to run all the 113 * children and update their d_flags to let them know p_inode 114 * doesn't care about them any more. 115 */ 116 dget(parent); 117 should_update_children = true; 118 } 119 120 spin_unlock(&dentry->d_lock); 121 122 if (send) { 123 /* we are notifying a parent so come up with the new mask which 124 * specifies these are events which came from a child. */ 125 mask |= FS_EVENT_ON_CHILD; 126 127 if (path) 128 fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH, 129 dentry->d_name.name, 0); 130 else 131 fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE, 132 dentry->d_name.name, 0); 133 dput(parent); 134 } 135 136 if (unlikely(should_update_children)) { 137 __fsnotify_update_child_dentry_flags(p_inode); 138 dput(parent); 139 } 140 } 141 EXPORT_SYMBOL_GPL(__fsnotify_parent); 142 143 static int send_to_group(struct inode *to_tell, struct vfsmount *mnt, 144 struct fsnotify_mark *inode_mark, 145 struct fsnotify_mark *vfsmount_mark, 146 __u32 mask, void *data, 147 int data_is, u32 cookie, 148 const unsigned char *file_name, 149 struct fsnotify_event **event) 150 { 151 struct fsnotify_group *group = inode_mark->group; 152 __u32 inode_test_mask = (mask & ~FS_EVENT_ON_CHILD); 153 __u32 vfsmount_test_mask = (mask & ~FS_EVENT_ON_CHILD); 154 155 pr_debug("%s: group=%p to_tell=%p mnt=%p mark=%p mask=%x data=%p" 156 " data_is=%d cookie=%d event=%p\n", __func__, group, to_tell, 157 mnt, inode_mark, mask, data, data_is, cookie, *event); 158 159 /* clear ignored on inode modification */ 160 if (mask & FS_MODIFY) { 161 if (inode_mark && 162 !(inode_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) 163 inode_mark->ignored_mask = 0; 164 if (vfsmount_mark && 165 !(vfsmount_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) 166 vfsmount_mark->ignored_mask = 0; 167 } 168 169 /* does the inode mark tell us to do something? */ 170 if (inode_mark) { 171 inode_test_mask &= inode_mark->mask; 172 inode_test_mask &= ~inode_mark->ignored_mask; 173 } 174 175 /* does the vfsmount_mark tell us to do something? */ 176 if (vfsmount_mark) { 177 vfsmount_test_mask &= vfsmount_mark->mask; 178 vfsmount_test_mask &= ~vfsmount_mark->ignored_mask; 179 if (inode_mark) 180 vfsmount_test_mask &= ~inode_mark->ignored_mask; 181 } 182 183 if (!inode_test_mask && !vfsmount_test_mask) 184 return 0; 185 186 if (group->ops->should_send_event(group, to_tell, inode_mark, 187 vfsmount_mark, mask, data, 188 data_is) == false) 189 return 0; 190 191 if (!*event) { 192 *event = fsnotify_create_event(to_tell, mask, data, 193 data_is, file_name, 194 cookie, GFP_KERNEL); 195 if (!*event) 196 return -ENOMEM; 197 } 198 return group->ops->handle_event(group, inode_mark, vfsmount_mark, *event); 199 } 200 201 /* 202 * This is the main call to fsnotify. The VFS calls into hook specific functions 203 * in linux/fsnotify.h. Those functions then in turn call here. Here will call 204 * out to all of the registered fsnotify_group. Those groups can then use the 205 * notification event in whatever means they feel necessary. 206 */ 207 int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 208 const unsigned char *file_name, u32 cookie) 209 { 210 struct hlist_node *inode_node, *vfsmount_node; 211 struct fsnotify_mark *inode_mark = NULL, *vfsmount_mark = NULL; 212 struct fsnotify_group *inode_group, *vfsmount_group; 213 struct fsnotify_event *event = NULL; 214 struct vfsmount *mnt; 215 int idx, ret = 0; 216 bool used_inode = false, used_vfsmount = false; 217 /* global tests shouldn't care about events on child only the specific event */ 218 __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD); 219 220 if (data_is == FSNOTIFY_EVENT_PATH) 221 mnt = ((struct path *)data)->mnt; 222 else 223 mnt = NULL; 224 225 /* 226 * if this is a modify event we may need to clear the ignored masks 227 * otherwise return if neither the inode nor the vfsmount care about 228 * this type of event. 229 */ 230 if (!(mask & FS_MODIFY) && 231 !(test_mask & to_tell->i_fsnotify_mask) && 232 !(mnt && test_mask & mnt->mnt_fsnotify_mask)) 233 return 0; 234 235 idx = srcu_read_lock(&fsnotify_mark_srcu); 236 237 if ((mask & FS_MODIFY) || 238 (test_mask & to_tell->i_fsnotify_mask)) 239 inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first, 240 &fsnotify_mark_srcu); 241 else 242 inode_node = NULL; 243 244 if (mnt) { 245 if ((mask & FS_MODIFY) || 246 (test_mask & mnt->mnt_fsnotify_mask)) 247 vfsmount_node = srcu_dereference(mnt->mnt_fsnotify_marks.first, 248 &fsnotify_mark_srcu); 249 else 250 vfsmount_node = NULL; 251 } else { 252 mnt = NULL; 253 vfsmount_node = NULL; 254 } 255 256 while (inode_node || vfsmount_node) { 257 if (inode_node) { 258 inode_mark = hlist_entry(srcu_dereference(inode_node, &fsnotify_mark_srcu), 259 struct fsnotify_mark, i.i_list); 260 inode_group = inode_mark->group; 261 } else 262 inode_group = (void *)-1; 263 264 if (vfsmount_node) { 265 vfsmount_mark = hlist_entry(srcu_dereference(vfsmount_node, &fsnotify_mark_srcu), 266 struct fsnotify_mark, m.m_list); 267 vfsmount_group = vfsmount_mark->group; 268 } else 269 vfsmount_group = (void *)-1; 270 271 if (inode_group < vfsmount_group) { 272 /* handle inode */ 273 send_to_group(to_tell, NULL, inode_mark, NULL, mask, data, 274 data_is, cookie, file_name, &event); 275 used_inode = true; 276 } else if (vfsmount_group < inode_group) { 277 send_to_group(to_tell, mnt, NULL, vfsmount_mark, mask, data, 278 data_is, cookie, file_name, &event); 279 used_vfsmount = true; 280 } else { 281 send_to_group(to_tell, mnt, inode_mark, vfsmount_mark, 282 mask, data, data_is, cookie, file_name, 283 &event); 284 used_vfsmount = true; 285 used_inode = true; 286 } 287 288 if (used_inode) 289 inode_node = srcu_dereference(inode_node->next, 290 &fsnotify_mark_srcu); 291 if (used_vfsmount) 292 vfsmount_node = srcu_dereference(vfsmount_node->next, 293 &fsnotify_mark_srcu); 294 } 295 296 srcu_read_unlock(&fsnotify_mark_srcu, idx); 297 /* 298 * fsnotify_create_event() took a reference so the event can't be cleaned 299 * up while we are still trying to add it to lists, drop that one. 300 */ 301 if (event) 302 fsnotify_put_event(event); 303 304 return ret; 305 } 306 EXPORT_SYMBOL_GPL(fsnotify); 307 308 static __init int fsnotify_init(void) 309 { 310 int ret; 311 312 BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23); 313 314 ret = init_srcu_struct(&fsnotify_mark_srcu); 315 if (ret) 316 panic("initializing fsnotify_mark_srcu"); 317 318 return 0; 319 } 320 core_initcall(fsnotify_init); 321