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(&inode->i_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 spin_lock(&alias->d_lock); 72 list_for_each_entry(child, &alias->d_subdirs, d_u.d_child) { 73 if (!child->d_inode) 74 continue; 75 76 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); 77 if (watched) 78 child->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; 79 else 80 child->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; 81 spin_unlock(&child->d_lock); 82 } 83 spin_unlock(&alias->d_lock); 84 } 85 spin_unlock(&inode->i_lock); 86 } 87 88 /* Notify this dentry's parent about a child's events. */ 89 int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) 90 { 91 struct dentry *parent; 92 struct inode *p_inode; 93 int ret = 0; 94 95 if (!dentry) 96 dentry = path->dentry; 97 98 if (!(dentry->d_flags & DCACHE_FSNOTIFY_PARENT_WATCHED)) 99 return 0; 100 101 parent = dget_parent(dentry); 102 p_inode = parent->d_inode; 103 104 if (unlikely(!fsnotify_inode_watches_children(p_inode))) 105 __fsnotify_update_child_dentry_flags(p_inode); 106 else if (p_inode->i_fsnotify_mask & mask) { 107 /* we are notifying a parent so come up with the new mask which 108 * specifies these are events which came from a child. */ 109 mask |= FS_EVENT_ON_CHILD; 110 111 if (path) 112 ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH, 113 dentry->d_name.name, 0); 114 else 115 ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE, 116 dentry->d_name.name, 0); 117 } 118 119 dput(parent); 120 121 return ret; 122 } 123 EXPORT_SYMBOL_GPL(__fsnotify_parent); 124 125 static int send_to_group(struct inode *to_tell, struct vfsmount *mnt, 126 struct fsnotify_mark *inode_mark, 127 struct fsnotify_mark *vfsmount_mark, 128 __u32 mask, void *data, 129 int data_is, u32 cookie, 130 const unsigned char *file_name, 131 struct fsnotify_event **event) 132 { 133 struct fsnotify_group *group = NULL; 134 __u32 inode_test_mask = 0; 135 __u32 vfsmount_test_mask = 0; 136 137 if (unlikely(!inode_mark && !vfsmount_mark)) { 138 BUG(); 139 return 0; 140 } 141 142 /* clear ignored on inode modification */ 143 if (mask & FS_MODIFY) { 144 if (inode_mark && 145 !(inode_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) 146 inode_mark->ignored_mask = 0; 147 if (vfsmount_mark && 148 !(vfsmount_mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)) 149 vfsmount_mark->ignored_mask = 0; 150 } 151 152 /* does the inode mark tell us to do something? */ 153 if (inode_mark) { 154 group = inode_mark->group; 155 inode_test_mask = (mask & ~FS_EVENT_ON_CHILD); 156 inode_test_mask &= inode_mark->mask; 157 inode_test_mask &= ~inode_mark->ignored_mask; 158 } 159 160 /* does the vfsmount_mark tell us to do something? */ 161 if (vfsmount_mark) { 162 vfsmount_test_mask = (mask & ~FS_EVENT_ON_CHILD); 163 group = vfsmount_mark->group; 164 vfsmount_test_mask &= vfsmount_mark->mask; 165 vfsmount_test_mask &= ~vfsmount_mark->ignored_mask; 166 if (inode_mark) 167 vfsmount_test_mask &= ~inode_mark->ignored_mask; 168 } 169 170 pr_debug("%s: group=%p to_tell=%p mnt=%p mask=%x inode_mark=%p" 171 " inode_test_mask=%x vfsmount_mark=%p vfsmount_test_mask=%x" 172 " data=%p data_is=%d cookie=%d event=%p\n", 173 __func__, group, to_tell, mnt, mask, inode_mark, 174 inode_test_mask, vfsmount_mark, vfsmount_test_mask, data, 175 data_is, cookie, *event); 176 177 if (!inode_test_mask && !vfsmount_test_mask) 178 return 0; 179 180 if (group->ops->should_send_event(group, to_tell, inode_mark, 181 vfsmount_mark, mask, data, 182 data_is) == false) 183 return 0; 184 185 if (!*event) { 186 *event = fsnotify_create_event(to_tell, mask, data, 187 data_is, file_name, 188 cookie, GFP_KERNEL); 189 if (!*event) 190 return -ENOMEM; 191 } 192 return group->ops->handle_event(group, inode_mark, vfsmount_mark, *event); 193 } 194 195 /* 196 * This is the main call to fsnotify. The VFS calls into hook specific functions 197 * in linux/fsnotify.h. Those functions then in turn call here. Here will call 198 * out to all of the registered fsnotify_group. Those groups can then use the 199 * notification event in whatever means they feel necessary. 200 */ 201 int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 202 const unsigned char *file_name, u32 cookie) 203 { 204 struct hlist_node *inode_node = NULL, *vfsmount_node = NULL; 205 struct fsnotify_mark *inode_mark = NULL, *vfsmount_mark = NULL; 206 struct fsnotify_group *inode_group, *vfsmount_group; 207 struct fsnotify_event *event = NULL; 208 struct vfsmount *mnt; 209 int idx, ret = 0; 210 /* global tests shouldn't care about events on child only the specific event */ 211 __u32 test_mask = (mask & ~FS_EVENT_ON_CHILD); 212 213 if (data_is == FSNOTIFY_EVENT_PATH) 214 mnt = ((struct path *)data)->mnt; 215 else 216 mnt = NULL; 217 218 /* 219 * if this is a modify event we may need to clear the ignored masks 220 * otherwise return if neither the inode nor the vfsmount care about 221 * this type of event. 222 */ 223 if (!(mask & FS_MODIFY) && 224 !(test_mask & to_tell->i_fsnotify_mask) && 225 !(mnt && test_mask & mnt->mnt_fsnotify_mask)) 226 return 0; 227 228 idx = srcu_read_lock(&fsnotify_mark_srcu); 229 230 if ((mask & FS_MODIFY) || 231 (test_mask & to_tell->i_fsnotify_mask)) 232 inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first, 233 &fsnotify_mark_srcu); 234 235 if (mnt && ((mask & FS_MODIFY) || 236 (test_mask & mnt->mnt_fsnotify_mask))) { 237 vfsmount_node = srcu_dereference(mnt->mnt_fsnotify_marks.first, 238 &fsnotify_mark_srcu); 239 inode_node = srcu_dereference(to_tell->i_fsnotify_marks.first, 240 &fsnotify_mark_srcu); 241 } 242 243 while (inode_node || vfsmount_node) { 244 inode_group = vfsmount_group = NULL; 245 246 if (inode_node) { 247 inode_mark = hlist_entry(srcu_dereference(inode_node, &fsnotify_mark_srcu), 248 struct fsnotify_mark, i.i_list); 249 inode_group = inode_mark->group; 250 } 251 252 if (vfsmount_node) { 253 vfsmount_mark = hlist_entry(srcu_dereference(vfsmount_node, &fsnotify_mark_srcu), 254 struct fsnotify_mark, m.m_list); 255 vfsmount_group = vfsmount_mark->group; 256 } 257 258 if (inode_group > vfsmount_group) { 259 /* handle inode */ 260 ret = send_to_group(to_tell, NULL, inode_mark, NULL, mask, data, 261 data_is, cookie, file_name, &event); 262 /* we didn't use the vfsmount_mark */ 263 vfsmount_group = NULL; 264 } else if (vfsmount_group > inode_group) { 265 ret = send_to_group(to_tell, mnt, NULL, vfsmount_mark, mask, data, 266 data_is, cookie, file_name, &event); 267 inode_group = NULL; 268 } else { 269 ret = send_to_group(to_tell, mnt, inode_mark, vfsmount_mark, 270 mask, data, data_is, cookie, file_name, 271 &event); 272 } 273 274 if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS)) 275 goto out; 276 277 if (inode_group) 278 inode_node = srcu_dereference(inode_node->next, 279 &fsnotify_mark_srcu); 280 if (vfsmount_group) 281 vfsmount_node = srcu_dereference(vfsmount_node->next, 282 &fsnotify_mark_srcu); 283 } 284 ret = 0; 285 out: 286 srcu_read_unlock(&fsnotify_mark_srcu, idx); 287 /* 288 * fsnotify_create_event() took a reference so the event can't be cleaned 289 * up while we are still trying to add it to lists, drop that one. 290 */ 291 if (event) 292 fsnotify_put_event(event); 293 294 return ret; 295 } 296 EXPORT_SYMBOL_GPL(fsnotify); 297 298 static __init int fsnotify_init(void) 299 { 300 int ret; 301 302 BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23); 303 304 ret = init_srcu_struct(&fsnotify_mark_srcu); 305 if (ret) 306 panic("initializing fsnotify_mark_srcu"); 307 308 return 0; 309 } 310 core_initcall(fsnotify_init); 311