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 92 if (!dentry) 93 dentry = path->dentry; 94 95 if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED)) 96 return; 97 98 parent = dget_parent(dentry); 99 p_inode = parent->d_inode; 100 101 if (unlikely(!fsnotify_inode_watches_children(p_inode))) 102 __fsnotify_update_child_dentry_flags(p_inode); 103 else if (p_inode->i_fsnotify_mask & mask) { 104 /* we are notifying a parent so come up with the new mask which 105 * specifies these are events which came from a child. */ 106 mask |= FS_EVENT_ON_CHILD; 107 108 if (path) 109 fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH, 110 dentry->d_name.name, 0); 111 else 112 fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE, 113 dentry->d_name.name, 0); 114 } 115 116 dput(parent); 117 } 118 EXPORT_SYMBOL_GPL(__fsnotify_parent); 119 120 static int send_to_group(struct inode *to_tell, struct vfsmount *mnt, 121 struct fsnotify_mark *inode_mark, 122 struct fsnotify_mark *vfsmount_mark, 123 __u32 mask, void *data, 124 int data_is, u32 cookie, 125 const unsigned char *file_name, 126 struct fsnotify_event **event) 127 { 128 struct fsnotify_group *group = NULL; 129 __u32 inode_test_mask = 0; 130 __u32 vfsmount_test_mask = 0; 131 132 if (unlikely(!inode_mark && !vfsmount_mark)) { 133 BUG(); 134 return 0; 135 } 136 137 /* clear ignored on inode modification */ 138 if (mask & FS_MODIFY) { 139 if (inode_mark && 140 !(inode_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) 141 inode_mark->ignored_mask = 0; 142 if (vfsmount_mark && 143 !(vfsmount_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) 144 vfsmount_mark->ignored_mask = 0; 145 } 146 147 /* does the inode mark tell us to do something? */ 148 if (inode_mark) { 149 group = inode_mark->group; 150 inode_test_mask = (mask & ~FS_EVENT_ON_CHILD); 151 inode_test_mask &= inode_mark->mask; 152 inode_test_mask &= ~inode_mark->ignored_mask; 153 } 154 155 /* does the vfsmount_mark tell us to do something? */ 156 if (vfsmount_mark) { 157 vfsmount_test_mask = (mask & ~FS_EVENT_ON_CHILD); 158 group = vfsmount_mark->group; 159 vfsmount_test_mask &= vfsmount_mark->mask; 160 vfsmount_test_mask &= ~vfsmount_mark->ignored_mask; 161 if (inode_mark) 162 vfsmount_test_mask &= ~inode_mark->ignored_mask; 163 } 164 165 pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x inode_mark=%p" 166 " inode_test_mask=%x vfsmount_mark=%p vfsmount_test_mask=%x" 167 " data=%p data_is=%d cookie=%d event=%p\n", 168 __func__, group, to_tell, mnt, mask, inode_mark, 169 inode_test_mask, vfsmount_mark, vfsmount_test_mask, data, 170 data_is, cookie, *event); 171 172 if (!inode_test_mask && !vfsmount_test_mask) 173 return 0; 174 175 if (group->ops->should_send_event(group, to_tell, inode_mark, 176 vfsmount_mark, mask, data, 177 data_is) == false) 178 return 0; 179 180 if (!*event) { 181 *event = fsnotify_create_event(to_tell, mask, data, 182 data_is, file_name, 183 cookie, GFP_KERNEL); 184 if (!*event) 185 return -ENOMEM; 186 } 187 return group->ops->handle_event(group, inode_mark, vfsmount_mark, *event); 188 } 189 190 /* 191 * This is the main call to fsnotify. The VFS calls into hook specific functions 192 * in linux/fsnotify.h. Those functions then in turn call here. Here will call 193 * out to all of the registered fsnotify_group. Those groups can then use the 194 * notification event in whatever means they feel necessary. 195 */ 196 int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 197 const unsigned char *file_name, u32 cookie) 198 { 199 struct hlist_node *inode_node = NULL, *vfsmount_node = NULL; 200 struct fsnotify_mark *inode_mark = NULL, *vfsmount_mark = NULL; 201 struct fsnotify_group *inode_group, *vfsmount_group; 202 struct fsnotify_event *event = NULL; 203 struct vfsmount *mnt; 204 int idx, ret = 0; 205 /* global tests shouldn't care about events on child only the specific event */ 206 __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD); 207 208 if (data_is == FSNOTIFY_EVENT_PATH) 209 mnt = ((struct path *)data)->mnt; 210 else 211 mnt = NULL; 212 213 /* 214 * if this is a modify event we may need to clear the ignored masks 215 * otherwise return if neither the inode nor the vfsmount care about 216 * this type of event. 217 */ 218 if (!(mask & FS_MODIFY) && 219 !(test_mask & to_tell->i_fsnotify_mask) && 220 !(mnt && test_mask & mnt->mnt_fsnotify_mask)) 221 return 0; 222 223 idx = srcu_read_lock(&fsnotify_mark_srcu); 224 225 if ((mask & FS_MODIFY) || 226 (test_mask & to_tell->i_fsnotify_mask)) 227 inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first, 228 &fsnotify_mark_srcu); 229 230 if (mnt && ((mask & FS_MODIFY) || 231 (test_mask & mnt->mnt_fsnotify_mask))) { 232 vfsmount_node = srcu_dereference(mnt->mnt_fsnotify_marks.first, 233 &fsnotify_mark_srcu); 234 inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first, 235 &fsnotify_mark_srcu); 236 } 237 238 while (inode_node || vfsmount_node) { 239 inode_group = vfsmount_group = NULL; 240 241 if (inode_node) { 242 inode_mark = hlist_entry(srcu_dereference(inode_node, &fsnotify_mark_srcu), 243 struct fsnotify_mark, i.i_list); 244 inode_group = inode_mark->group; 245 } 246 247 if (vfsmount_node) { 248 vfsmount_mark = hlist_entry(srcu_dereference(vfsmount_node, &fsnotify_mark_srcu), 249 struct fsnotify_mark, m.m_list); 250 vfsmount_group = vfsmount_mark->group; 251 } 252 253 if (inode_group > vfsmount_group) { 254 /* handle inode */ 255 send_to_group(to_tell, NULL, inode_mark, NULL, mask, data, 256 data_is, cookie, file_name, &event); 257 /* we didn't use the vfsmount_mark */ 258 vfsmount_group = NULL; 259 } else if (vfsmount_group > inode_group) { 260 send_to_group(to_tell, mnt, NULL, vfsmount_mark, mask, data, 261 data_is, cookie, file_name, &event); 262 inode_group = NULL; 263 } else { 264 send_to_group(to_tell, mnt, inode_mark, vfsmount_mark, 265 mask, data, data_is, cookie, file_name, 266 &event); 267 } 268 269 if (inode_group) 270 inode_node = srcu_dereference(inode_node->next, 271 &fsnotify_mark_srcu); 272 if (vfsmount_group) 273 vfsmount_node = srcu_dereference(vfsmount_node->next, 274 &fsnotify_mark_srcu); 275 } 276 277 srcu_read_unlock(&fsnotify_mark_srcu, idx); 278 /* 279 * fsnotify_create_event() took a reference so the event can't be cleaned 280 * up while we are still trying to add it to lists, drop that one. 281 */ 282 if (event) 283 fsnotify_put_event(event); 284 285 return ret; 286 } 287 EXPORT_SYMBOL_GPL(fsnotify); 288 289 static __init int fsnotify_init(void) 290 { 291 int ret; 292 293 BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23); 294 295 ret = init_srcu_struct(&fsnotify_mark_srcu); 296 if (ret) 297 panic("initializing fsnotify_mark_srcu"); 298 299 return 0; 300 } 301 core_initcall(fsnotify_init); 302